Claim 1: Jesus didn’t speak about same-sex marriage, so he’s at least neutral if not open to it. What Jesus doesn’t condemn, we shouldn’t condemn.
This is an argument from silence, but the silence doesn’t take place in a vacuum. Jesus addresses and defines marriage in Matthew 19:4–6 and Mark 10:6–9 using both Genesis 1:26–27 and Genesis 2:24 to parse it out. Here Jesus defines and affirms marriage as between a man and a woman, a reflection of the fact that God made us male and female to care for creation together. With this definition, same-sex marriage is excluded. Had Jesus wished to extend the right of marriage beyond this definition, here was his opportunity. But he didn’t take it.
Jesus never discussed same-sex marriage because the way he defined marriage already excluded it. He was not as silent on the topic as some claim.
An argument from silence. Know your logical fallacies.
This article has some great answers to the questions that, if you are a Christian, you have heard a few too many times.