Attempting to win Christians over to their side, same-sex “marriage" proponents often assert that Jesus would approve of their agenda. They claim that Jesus never said anything at all about homosexuality. Not once do the gospels record him condemning homosexual acts as being sinful. Therefore, the activists claim, Jesus would approve of same-sex “marriage" and Christians should be supportive.
Although it is true that the gospels do not record Jesus directly condemning homosexual acts, to conclude on this basis that he in any way approved of them is faulty reasoning. It commits a logical fallacy known as argumentum a silentio (Latin for “argument from silence"). “Jesus is not on record against it so he must be for it." Such an argument bases its conclusion on a supposed lack of evidence to the contrary rather than on the existence of any evidence one way or the other. In reality, lack of evidence does not prove anything.
The fact that the gospels do not contain a record of Jesus doing something does not mean that he did not do it. It could be that the gospel writers simply did not record it. The gospels do not contain an exhaustive record of Jesus’ teaching. John tells us as much at the end of his gospel (John 21:25):
But there are also many other things which Jesus did; were every one of them to be written, I suppose that the world itself could not contain the books that would be written.
The Catechism of the Catholic Church (514) addresses this as well:
Many things about Jesus of interest to human curiosity do not figure in the Gospels. Almost nothing is said about his hidden life at Nazareth, and even a great part of his public life is not recounted.
So, it could be that Jesus did directly condemn homosexual acts but his condemnations were not recorded in the gospels. In fact, it is reasonable to assert that he did do so because homosexual acts were condemned in the Old Testament before Jesus as well as in the New Testament after him.
In the New Testament, it is primarily in Paul’s letters that homosexual acts are directly condemned. In his letter to the Galatians, Paul reminds us where he got his teaching (Gal 1:11-12):
For I would have you know, brethren, that the gospel which was preached by me is not man's gospel. For I did not receive it from man, nor was I taught it, but it came through a revelation of Jesus Christ.
Paul was the last apostle to be sent by Jesus (cf. 1 Cor 15:8) and we should expect that he received the same assurances that Jesus provided to the other apostles. Jesus promised his apostles that the Holy Spirit would (among other things) “bring to your remembrance all that I have said to you" (John 14:26).
Paul certainly shared in this assurance. That being the case, his teaching on homosexuality may very well be what he remembered Jesus saying to him in a revelation.
Additionally, when Jesus sent out representatives he told them, “He who hears you hears me, and he who rejects you rejects me, and he who rejects me rejects him who sent me” (Luke 10:16). Thus, since Paul was sent by Jesus, when we “hear" him in his letters, we also hear Jesus.
There really is no doubt that Jesus condemned homosexual acts as sinful so do not be fooled by the faulty reasoning of activists.