You are wrong in believing Christianity is about forgiveness. Christianity is about loving God, and to love God one has to keep God’s Commandments. Having homosexual sex is not keeping God’s Commandments.
(John 14: 23) “Anyone who loves me will keep my word and my Father will love him, and we shall come to him and make a home in him.”
(John 14:21) “Anybody who receives my commandments and keeps them will be one who loves me; and anybody who loves me will be loved by My Father, and I shall love him and show myself to him.”
The following scripture leaves much doubt that Jesus is going to forgive those who deliberately disobey him.
(John 12:47-48) “If anyone hears my words and does not keep them faithfully, it is not I who shall condemn him, since I have come not to condemn the world, but to save the world: he who rejects me and refuses my words has his judge already: the word itself that I have spoken will be his judge on the last day.”