We are in an interesting time in American legal and cultural history. On the one hand, the advance of modernity is throwing down traditional legal barriers to same-sex so-called marriage and opening up new doors to homosexuals to not only practice homosexuality but have their unions recognized by the State. On the other hand, there is a growing movement of concerned Americans protesting infringements against religious liberty by the new regime which in many cases compels Christians to support things contrary to their faith, either implicitly or explicitly. These two contrary movements have come crashing together in the controversies over whether Christian bakers, florists, restaurants, etc. are legally obligated to provide services for homosexual weddings, the so-called "wedding cake" dilemma, based on a famous court case where a Christian baker refused to provide a wedding cake for a homosexual ceremony and was sued for discrimination.
I have spent the past several months engaged in various online debates with well-meaning but errant individuals who think that Christians ought to just go with the flow and bake wedding cakes for homosexual ceremonies. In this post, I present a long Q&A cobbled together from these various debates. I have used the example of a baker being asked to provide a wedding cake for a homosexual wedding, but it could be any service.
I also admit that how a Christian behaves in a certain situation is a thorny problem, one that admits of various legal and moral nuances. However, it also seems to me that the simplest and best way to approach this problem is to understand that it is essentially no different than when the Roman persecutors attempted, by legal and physical threats, to make Christians apostasize by pinching incense to Caesar. To me, what Christian business people are being asked is to deny the Faith by affirming as good something that is evil. Therefore, my personal opinion is that Christians ought to resist this with all their might, and I think the Church's tradition is with me here as well.
I should also mention, I do not anticipate a person who is in favor of gay marriage will find these arguments convincing; rather, I have put this together to help Christians clarify their thinking when dialoguing with these folks. So this is not an entire apologia of the Church's teaching; rather, it is a series of answers to practical questions. We understand that real life is going to be more complex than the scenarios dealt with here, and that ultimately people need to follow their conscience as best they are able.
Finally, while remembering the example of the Roman martyrs, we also recall the admonitions of the early Church for Christians, who encouraged their brethren to suffer manfully when apprehended but not to volunteer themselves for martyrdom needlessly, as the Martyrdom of Polycarp says, "we do not commend those who give themselves up [to suffering], seeing the Gospel does not teach so to do” [Martyrdom of Polycarp, 4]. Be willing to take a stand, but be mindful of how and when you take your stand.
So, on to the question and answer...
Q. Why can't a Christian simply bake a cake for a gay wedding?
A. Homosexual actions have always been perceived as gravely depraved acts in Christian tradition. This is found in the Scripture (cf. Rom. 1:24-28, 1 Cor. 6:9, 1 Tim. 1:10) and reaffirmed in the modern Catechism of the Catholic Church, which states: "Tradition has always declared that homosexual acts are intrinsically disordered. They are contrary to the natural law. They close the sexual act to the gift of life. They do not proceed from a genuine affective and sexual complementarity. Under no circumstances can they be approved" . Because they are contrary to natural law, they can never form the basis for any marriage, which must be between one man and one woman exclusively. Hence no Catholic can in good conscience participate in a homosexual "wedding" since homosexual relations are intrinsically evil.
Q. But baking a cake for a gay wedding is not participating in the wedding.
A. What does it mean to "participate"? Participation does not mean merely attending, but offering any material support to. Homosexual acts and the attempt to engage in homosexual are both considered sinful by Catholics. Therefore, to offer material support to such actions is itself sinful. Catholic tradition denotes nine ways one can be an accessory to the sin of another :
I. By counsel (advising one to commit a sin)
II. By command (ordering a sin to be committed)
III. By consent (agreeing with the sin being committed)
IV. By provocation (daring or challenging one to commit a sin)
V. By praise or flattery (praising someone for committing a sin)
VI. By concealment (helping that person hide their sin)
VII. By partaking (actually participating in the sin itself)
VIII. By silence (refusing to speak out against the sin)
IX. By defense of the ill done (defending the commission of the sin)
In any one of these cases, one can become guilty of the sin of another by their complicity. This means not only are homosexual "marriages" sinful, but a person who is an accessory to facilitating such a marriage is also guilty of a sin. The baker who refuses a wedding cake to a homosexual "marriage" ceremony refuses not primarily because he disagrees with gay marriage, but because to cooperate in the gay marriage is sinful for the baker. According to the list above, providing a cake (or floral arrangement, or whatever) to a homosexual "wedding" is an accessory to sin by partaking, insofar as the cake is material support to the gay wedding, by silence, insofar as the baker does not object to gay marriage and by the principle of qui tacet consentire videtur ("silence is consent"); it may be argued that the baker also consents to the ceremony, at least implicitly.
Thus, one can see that the baker who bakes a wedding cake for a homosexual "marriage" does in fact participate in the ceremony several different ways, insofar as his service he renders offers the ceremony material support. Thus, in our opinion, to do so would constitute a grave sin for that baker because he would be an accessory to the sin of attempting to enter into a homosexual "marriage".
Q. Is it wrong to bake a cake for a single mother celebrating the birth of her child?
A. No. It would not be wrong for a baker to bake a cake for a single mother celebrating the birth of her child. This would be perfectly acceptable.
Q. Why not? You are being a hypocrite and saying one sin is worse than another. By your standards, a mother who has a child out of wedlock is just as much a sinner as an active homosexual.
A. There is nothing sinful about a woman celebrating the birth of a child. There is something sinful about celebrating an attempted "marriage" between two persons of the same sex.
A woman may have committed the sin of fornication, by which she got pregnant. But the sin of fornication is distinct from the act of giving birth. To bake a cake celebrating the birth of a child does not offer material support to the sin of fornication. Here, one is celebrating a birth, not celebrating fornication. Now, if the woman requested a cake celebrating the act of fornication, this would be different - but of course that would most likely never happen. In the case of the homosexual wedding, the cake is being utilized to facilitate a same sex "marriage" ceremony, which is immoral.
It must be remembered, this is not about punishing sinners for past sins already committed or refusing to associate with people who have made mistakes; this is about refusing to cooperate in sins currently being committed and offering material support to objectively immoral activities.
Q. Then if you were consistent, shouldn't you also refuse to pay your taxes since tax dollars fund immoral things?
A. It is written, "Render to Caesar what is Caesar and to God what is God's", and "Pay all of them their dues, taxes to whom taxes are due, revenue to whom revenue is due" (cf. Mark 12:17, Rom. 13:7). Paying taxes is an obligation laid upon us by God Himself; supporting same-sex "marriage" is a sin which Catholics must resist.
Furthermore, while the government funds some immoral activities, there is a difference here, and it has to do with certitude. While our tax dollars in general may fund evil things, there is no way to be certain that my specific tax dollars are funding something evil. Suppose I paid $1,000 in taxes to the federal government last year. Did it go to fund Planned Parenthood somewhere? Did it pay to bomb some innocent Pakistanis from a drone? Or did it go towards a freeway, or to fund research about dolphins, or maybe to some other needful improvement? How did that $1,000 get allocated? There is no way to know; I don't have certitude that my particular money was funding anything and there is no way to know. Because I don't have certitude on what this money is going for, I have no justification for not paying taxes. That's why Jesus could say "Render unto Caesar what is Caesar's" and St. Paul could say "Pay taxes to whom taxes are due" even though the Roman government was involved in monstrous crimes against humanity on a regular basis. Taxes, by their nature, go to a variety of purposes, and there is no way to know how your money is used in particular.
When I bake a cake for a gay wedding, on the other hand, I have 100% certitude that I am voluntarily and directly complying in evil with my personal money and resources. My resources are going immediately and directly to provide material support for the gay wedding; there is no question of allocation. The complicity is much more direct, much more certain, much more voluntary, and hence much more grave.
Furthermore, the Catechism of the Catholic Church states that even if the government is engaged in activities that are immoral, citizens are not exempt from obeying the government in what pertains to the common good. Citing Gaudium et Spes, it says:
"When citizens are under the oppression of a public authority which oversteps its competence, they should still not refuse to give or to do what is objectively demanded of them by the common good; but it is legitimate for them to defend their own rights and those of their fellow citizens against the abuse of this authority within the limits of the natural law and the Law of the Gospel" 
Because the Catechism identifies taxes as "morally obligatory" because of our "Submission to authority and co-responsibility for the common good", this means the government's immoral use of some of our tax dollars does not exempt us from the obligation to pay them . If it is obligatory to pay taxes even if the government is acting immorally, it can certainly not be sinful. Offering material support to homosexual marriages, on the other hand, is sinful, as we have explained above.
Q. Then shouldn't you also boycott companies who we know for certain fund immoral activities?
A. Probably. Again, as in the case of paying taxes, you do not know for sure how your money is being spent in particular, but if you still know the company is doing evil with the proceeds (supporting abortion, same sex marriage, etc.), then a boycott would be appropriate. The big difference here is we have a moral obligation to pay taxes, but no moral obligation to buy from a particular company or any company. Where there is certain evidence that money is being used to fund intrinsically evil activities, a Christian should withhold their money.
This does not mean a Christian is obligated to do investigative research to discover what every single company is doing with their money; St. Paul's principle regarding meat sacrificed to idols is helpful here. St. Paul says in 1 Cor. 10:
"Eat whatever is sold in the meat market without raising any question on the ground of conscience. For “the earth is the Lord’s, and everything in it.” If one of the unbelievers invites you to dinner and you are disposed to go, eat whatever is set before you without raising any question on the ground of conscience. (But if someone says to you, “This has been offered in sacrifice,” then out of consideration for the man who informed you, and for conscience’ sake— I mean his conscience, not yours—do not eat it.) For why should my liberty be determined by another man’s scruples? If I partake with thankfulness, why am I denounced because of that for which I give thanks?" (1 Cor. 10:25-30)
Now this is a little different from the sorts of cases we are discussing, but still relevant. We can go to a store and shop and buy whatever we wish "without raising any question on the ground of conscience". But if we later come to find out that a particular business is supporting something immoral, at that point it would be appropriate to stop supporting that company. Yes, we must act according to our knowledge; no, we need not go out of our way becoming investigative reporters on the expenditures of every company we do business with.
Q. If two heterosexuals order a wedding cake, why don't you quiz them to find out if they are living in sin?
A. Well, again, we are under no obligation to go out of our way to investigate these matters. When we buy from someone, or when someone comes to buy from us, we presume everything is aright unless we have reason to suspect otherwise, following St. Paul's principle.
The difference, of course, is that when a heterosexual person comes in and asks for a wedding cake, it is not evident whether they are living in sin. Many heterosexuals get married without ever having lived together. Thus, unless I am going to quiz him on his living arrangements - which we are not morally obligated to do - we have no cause for suspicion. A homosexual who asks for a wedding cake for a gay marriage, on the other hand, by the very act of asking reveals that they are living in sin, since homosexual relationships are immoral and intrinsically disordered.
Furthermore, even if a heterosexual couple is living in sin, this condition ends when they get married; i.e., a man and woman who are fornicating are no longer living in sin after they enter into marriage. A homosexual couple, on the other hand, do not cease to live in sin by purporting to contract marriage, because of course there is no such thing as a homosexual "marriage." The homosexual state of sin continues so long as the homosexual relationship continues. This is why a baker may legitimately bake a cake for a heterosexual wedding without making any inquiries, but that same baker when asked to bake a cake for a homosexual ceremony can refuse without asking any further questions; the mere fact that the cake is requested for a homosexual ceremony provides him with all the information he needs.
Q. You are making one sin worse than another.
A. Well, not all sins are equal. That is a Protestant notion. Catholic Tradition has divided sins up according to their gravity, mortal and venial. But not even all mortal sins are of equal gravity. Tradition distinguishes certain sins that "cry to heaven" for judgment from God. There are four of these sins: murder (Gn 4:10), sodomy (Gn 18:20-21), oppression of the poor (Ex 2:23), and defrauding workers of their just wages (Jas 5:4). These sins are considered so grave that they demand justice from God. This is also taught in the Catechism (CCC 1867).
Furthermore, some sins are against nature itself. A man who fornicates with a woman commits a serious sin, but it is not contrary to nature because it is natural for men to be attracted to women. Sodomy, on the other hand, is not only a serious sin but actually contrary to nature, so in a sense, it is a worse sin than others.
Q. Maybe so, but don't you think Catholics are obsessed with sexual issues? There are so many other problems out there that need addressing.
A. The tactic of playing social justice issues against life issues is a stupid false dichotomy. It may be true that the Catholics in the United States make a lot more noise defending traditional marriage than other issues. But does this fact mean that we Catholics are "obsessed" with these issues and see them as the most important Catholic teachings?
Here's the thing. YES, there are lots of other Catholic teachings, and YES, there are lots of other sins; alcoholism, poverty and child abuse are certainly very serious problems that need to be addressed. But (and this is a very serious but), no one is out there trying to redefine the evils of alcoholism, poverty and child abuse and trying to turn them into positive goods. There are no such groups as the "Society for the Promotion of Alcoholism" or the "Child Abuse Supporters Network." There are no mass protests of people chanting, "More poverty! More poverty!" No one is redefining theft as a virtue, or advocating for lying as just one of many acceptable forms of communication, or touting the benefits of drunkenness. In none of these cases is society moving to redefine sin into goodness or vice into virtue. The secular world, by and large, still understands alcoholism, child abuse, etc. to be evils, or at least socially undesirable.
But of course, nobody is proposing to promote drunkenness or redefine lying as a virtue. But people are in fact doing this with abortion, homosexuality and euthanasia, three acts that the entire Western Tradition has seen as gravely evil and depraved until relatively recently. In these cases of homosexuality, we do in fact have a society-wide attempt to redefine as positive goods things that were unanimously understood to be evil.
Thus, it is certainly not that the Church is "obsessed" abortion, homosexuality and euthanasia; on the contrary, it is our corrupt culture that is obsessed with redefining the morality of acts that have always been viewed as evil. The Church is not attacking a particular point with any special vehemence; it is simply putting its finger in the dyke at the point of the leak, or deflecting a specific blow aimed at a specific spot on the Body (See also: "Alleged Catholic "Obsession" With Homosexuality and Abortion").
Q. But the Catechism says we are not to discriminate against homosexuals. Isn't this discrimination?
A. No homosexual is being discriminated against because no homosexual is being denied a service. The issue isn't that Christian bakers will not service homosexuals, but that Christian bakers will not participate in homosexual "weddings." The question isn't whether a man must do business with a homosexual, but whether he can be compelled to support a particular ceremony. A gay man who comes in and asks for a cake from a Christian baker would get it without complaint; there is nothing objectionable to baking a cake for a gay man, working on a homosexual's car, doing a homosexual's taxes, etc. Doing business with homosexuals is not the issue. The issue is offering material support to a same sex wedding ceremony. It is not immoral or sinful to do business with a homosexual, just like it is not wrong to do business with a pagan or atheist. It is wrong, however, to participate in a same sex wedding ceremony or offer it material support.
Q. I disagree. This is discrimination. Discrimination is wrong, no matter how you slice it.
A. Fine. Let's run with that and grant, for the sake of argument, that this is discrimination. Is all discrimination inherently wrong? The 1992 Vatican document with the cumbersome name "Some Considerations Concerning the Response to Legislative Proposals on the Non-Discrimination of Homosexual Persons", published by the Congregation for the Doctrine of the Faith under the auspices of future-pope Cardinal Ratzinger notes:
“One tactic used is to protest that any and all criticism of or reservations about homosexual people, their activity and lifestyle, are simply diverse forms of unjust discrimination”... “Sexual orientation” does not constitute a quality comparable to race, ethnic background, etc. in respect to non-discrimination. Unlike these, homosexual orientation is an objective disorder and evokes moral concern. There are areas in which it is not unjust discrimination to take sexual orientation into account, for example, in the placement of children for adoption or foster care, in employment of teachers or athletic coaches, and in military recruitment" .
In other words, not all discrimination is unjust. There are times when sexual orientation must be taken into account - such as when a Christian is compelled to offer material support to an immoral homosexual "wedding." A 2003 CDF document "Considerations Regarding Proposals to Give Legal Recognition to Unions Between Homosexual Persons" reaffirms this teaching, stating:
"The principles of respect and non-discrimination cannot be invoked to support legal recognition of homosexual unions. Differentiating between persons or refusing social recognition or benefits is unacceptable only when it is contrary to justice. The denial of the social and legal status of marriage to forms of cohabitation that are not and cannot be marital is not opposed to justice; on the contrary, justice requires it." 
Discrimination is not inherently unjust; it only becomes unjust when it is contrary to justice. In the question of extending legal recognition to sodomy and other forms of cohabitation as equal with marriage, justice actually demands that we be discriminating. Thus, even if this were a case of discrimination, it is a discrimination that is not unjust.
Q. This sounds too complex...too legalistic.
A. First, this would not be a complicated problem if the State was respecting its boundaries and not compelling Christians to compromise their conscience. Yes, it is complex. Life is a complicated thing when you get down to the nitty-gritty of what one ought to do in any given circumstance. It is the State who chose this fight by creating an alleged "right" to same-sex marriage, not Christians.
Q. I don't feel any love. We are called to be loving. Christ's commandment was to love one another. How is this loving?
A. Love sounds good, but love is subordinated to truth. Love presupposes that we know what is good and true. Without goodness and truth, there is no love. It is not "loving" to help someone carry out actions that are immoral; it is not loving to drive a girl to have an abortion, or to procure a hotel room for an adulterous rendezvous. It is not love to facilitate a homosexual "marriage", and it is really irrelevant what you "feel" about it. Love is not a matter of feelings. If love were a matter of feelings, one must explain why any group - whether two men, multiple men and women, men and animals, people and inanimate objects - cannot also get married if marriage is simply a matter of "love."
And to narrow Christ's message down to merely love - and a love divorced from truth - is a grave misrepresentation of the Gospel. Jesus also says "Go and sin no more" (John 8:11). Jesus Himself also says "But the fearful, and unbelieving, and the abominable, and murderers, the sexually immoral, and sorcerers, and idolaters, and all liars, they shall have their portion in the pool burning with fire and brimstone, which is the second death" (Rev. 21:8). Can it be love to help two men practice sexual immorality when we know it can lead to eternal damnation?
Q. How should Christians act in states where gay marriage is the law of the land?
A. Here again I will defer to the CDF document on legal recognition of same sex unions:
"In those situations where homosexual unions have been legally recognized or have been given the legal status and rights belonging to marriage, clear and emphatic opposition is a duty. One must refrain from any kind of formal cooperation in the enactment or application of such gravely unjust laws and, as far as possible, from material cooperation on the level of their application. In this area, everyone can exercise the right to conscientious objection" 
Obviously, these questions do not cover every contingency, and there are many more factors that could be considered, such as whether the assistance is material or formal, whether it is proximate or remote to the evil act, who is the agent, etc. For example, what about a worker at a banquet facility who upon showing up to work finds that he must serve tables at a reception for a homosexual wedding? What about when a cake for a gay wedding is requested from a lower employee whose responsibility is simply to take orders and has no authority to deny any customer? What should they do, and what level of complicity would they have?
As mentioned above, the proliferation of homo-fascism is resulting in a lot of moral dilemmas in which Christians in business are being forced to quickly decide how they will react. Though the specific circumstances are legion, it is our contention that Christians have a moral obligation to not offer material support to homosexual "weddings", and that to refuse to participate in such activities is not unjust discrimination.
 CCC 2357
 These are part of Catholic Tradition, but can be found in the 1962 Roman Missal under the heading "The Most Necessary Prayers."
 CCC 2242; Gaudium et Spes 74 § 5.
 CCC 2240
 "Some Considerations Concerning the Response to Legislative Proposals on the Non-Discrimination of Homosexual Persons", Congregation for the Doctrine of the Faith, 1992, available online at http://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_19920724_homosexual-persons_en.html <accessed 16 Apr. 2015>
 "Considerations Regarding Proposals to Give Legal Recognition to Unions Between Homosexual Persons", Congregation for the Doctrine of the Faith, 2003, http://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20030731_homosexual-unions_en.html <accessed 16 Apr. 2015>
 ibid., 5