Question: Is gay marriage sinful?


Recently I have seen otherwise devote Catholics start to argue that gay marriage is in fact not sinful because those engaged in it, do not have the knowledge or aren’t in a place to truly understand, and so they aren’t culpable and therefore the act of getting married to someone of another sex, isn’t sinful. It was my limited understanding that while knowledge could remove or lesson culpability, that it didn’t change the fact that the act itself (and this could be anything it doesn’t have to be gay marriage) is a sin. Am I just misunderstanding or is the act of gay marriage a sin?

Thank you!


So, for mortal sin to be committed, 3 items must be fulfilled:
-grave matter (eg murder,adultery, or, in this case, same-sex relations)
-full knowledge (The persons committing the sin must know it is grave matter)
-full consent (the persons sinning are doing it freely, without coercion)

So, for the example you explained above, while grave matter and full consent are there, the full knowledge is most likely missing.

So, to put it simply/colloquially, yes, gay marriage is a grave sin.

To put it technically correct, those 3 above conditions must be met.

  1. According to Catholic teaching, gay marriage is objectively sinful in the sense that it is disordered and not in accord with God’s will.

But that’s not the whole story. Simply entering into a gay marriage does not mean one is subjectively responsible, that is, committing a sin.

  1. For someone to be subjectively culpable, one must know they are acting against God’s will and do so freely.

I don’t want this post to seem 100% black and white. Because it’s not. What is meant by “marriage”? Is the gay couple in a sexual relationship? Have they merely entered into a civil union, but are celibate friends? What is the concrete living situation?


Yes, as others have stated it is objectively sinful and a morally wrong act. They may or may not be culpable.


If your mindset is of this world and have no knowledge of God and his scripture, then gay marriage can be seen as a social justice issue that discriminates against them.

But if you fear God, and want eternal salvation of your soul, then you wouldn’t want to do any mortal sin that would keep you out of heaven. The act of sodomy is one of many sins punishable by hell fire. Fornicators (Sex outside marriage) fall under this punishment also.

1 Corinthians 6:9 Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, 10 nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God.


I think it’s a matter of semantics. Entering into a “gay marriage” is almost certainly grave matter, and it could be referred to as a grave sin for that reason. However, a particular person commits a grave sin only when three conditions are fulfilled:

  • The act is gravely wrong/immoral.
  • The person committing the act knows that the act in gravely wrong/immoral.
  • The person committing the act does so by his own free choice (e.g., no coercion).

Therefore, it is possible that a person could enter a “gay marriage” without buing guilty of a grave sin, if that person did not understand that there was anything wrong with the act, or if the person was coerced. But we also need to be careful to remember two points:

  1. We have an obligation to form our consciences correctly. If we remain intentionally ignorant of right and wrong, this ignorance may not be a valid excuse for committing a sin.
  2. Only God judges a person’s culpability for a sin. So if a Catholic says that a particular action is gravely sinful, that usually means that it is grave matter – meaning that someone undertaking that action would be committing a grave sin, if the other criteria are satisfied (but only God can judge those other criteria).


Short answer; yes. Very much so. It isn’t marriage by definition.


@gcshapero and others,

One thing we have to be careful about is being precise when we say gay marriage is “grave sin.”

For, what do we really mean by this? Since marriage is, by nature, heterosexual, then we can’t mean that it’s gravely wrong for two men to enter into marriage – for that is impossible. So what are we saying? Are we saying it’s “gravely sinful” to enter into a same-sex civil union, even if there’s no sexual activity? Is it only if same-sex sexual activity is involved? Is it publicly professing marriage to be homosexual that is gravely wrong?


I was speaking very generally. Being more precise, it’s because marriage is defined by the union being uniquely that of a man and a woman for the sake of openness to procreation and serving within the domestic Church.

Now there are also Josephite marriages, but from my understand, this is a very specific, rare, and unique form which would mean a willingness to abstain despite the ability to consummate, and it requires permission from the Church.

Even a marriage that is hetero but uses contraception is in trouble, though same-sex by default interferes with this criteria so it cannot be a valid marriage.


But this doesn’t answer why entering into a gay marriage is gravely sinful.

Is it the assertion that marriage is NOT this definition that is gravely sinful?

Is it that same-sex marriage includes sexual activity that is deemed gravely sinful by the Church?

Is it merely a civil union by two people of the same sex?

What is it?


I would say the primary probem is that a “gay marriage” is a public celebration of a sexual relationship between two people of the same sex. A secondary problem (but still potentially a very serious one) is that it makes a mockery of a sacrament.


So what if a same-sex, committed gay couple (whether celibate or sexually active) didn’t have a public celebration? Would that mean it is no longer sinful?

And what if the gay couple didn’t propose they were mocking the sacrament, but instead simply finding a civil way to live together?


Lutherans, on the other hand, don’t consider marriage to be a sacrament, so gay Lutherans wouldn’t have the problem you describe. :wink:



I could see a gay Catholic affirm the Catholic understanding of the sacrament of marriage (as heterosexual, etc.) and yet still find a same-sex civil union to be a path for himself in the Church.

I’m scared to even say that on these forums, but it’s part of the question of identifying WHAT is gravely sinful about “gay marriage,” since it’s not actually marriage (in the Catholic sense). There are as many answers as posters, I suppose…


In Catholic thought,
Gay sex is a sin.
Gay marriage kinda doesn’t really exist.
Oh, we have the legal permission to do so.
But theologically and per natural law, it’s not a thing…


Marriage by its nature is a public union. Unless they keep their “marriage” completely secret, then it is public. And if they are filing taxes as a legally married couple, or claiming other governmental benefits that are reserved to marriage, then that again makes their union public. But even if you remove the word “public” from my previous post, it is still problematic, because of the type of sexual union that is being celebrated or affirmed.

As for mocking the sacrament, I would see an attempted marriage of two men or of two women as a mockery of the sacrament of marriage, whether that is what is intended or not.

However, I would like to understand more what you meant by “instead simply finding a civil way to live together.” Are you envisioning two people who are living together chastely – as brothers (or sisters) or as friends or as roommates? If so, then why would they need to attempt to enter into marriage in order to establish this kind of living arrangement?


If two divorced people get married and their former spouses are still living, would you also consider their marriage to be a mockery of the sacrament of marriage?

Also, if two men are getting married and they aren’t Catholic, then why should a Catholic understanding of marriage prevent them from getting married? People can’t refrain from doing things because someone somewhere is offended by what they are doing.


Perhaps it also would be a mockery of marriage, but if so, then maybe to a lesser extent? On the one hand, at least they understand that marriage is meant to be a union based on a complementary sexual relationship. So they get that one very fundamental issue right. However, on the other hand, they don’t get the lifelong commitment part right, and that is very fundamental too.

Perhaps because divorce is so widespread, this type of union seems less shocking, or less of a mockery. But perhaps it shouldn’t. I would have to give that question some more thought.


From their perspective, it shouldn’t. And I never said that two men shouldn’t attempt to marry for the reason that their attempt would offend me.

But God established marriage for everyone, and all people can validly participate in marriage, whether Catholic, Orthodox, Protestant, Jewish, Muslim, Hindu, Buddhist, Pagan, Atheist, etc. Marriage is a sacrament only for those who are baptized as Christians, but it is still a very important and very real union for everyone. God is real whether people believe or not, and God’s plan for marriage is real whether they believe or not.


Yes. Gay marriage is a mortal sin in the Catholic church!

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit