Your responsibilty is to pray for their conversion.
Not to damn them.
Yes, I know how difficult that is.
I always go back to the story about the adulteress who was to be stoned by the mob. Jesus stopped them from condemning her to death and stoning her. But he told her to go and sin no more.
Many on the left read the words “neither do I condemn you” and use the modern definition to read it as “neither do I criticize you”. Then they leave out “go and sin no more” entirely. He didn’t tell her that what she was doing was no longer a sin now that he had come into the world to save it.
This is also the answer to those who say “Well, if we are to apply Biblical law to homosexuality, why don’t we sell our daughters into slavery if they have extra-marital sex?” It’s because we are to condemn the sin but not the sinner. Forgive them - but tell them that it’s still sinful and they need to stop.