Romans 1
25 They exchanged the truth about God for a lie, and worshiped and served created things rather than the Creator—who is forever praised. Amen.
26 Because of this, God gave them over to shameful lusts. Even their women exchanged natural sexual relations for unnatural ones. 27 In the same way the men also abandoned natural relations with women and were inflamed with lust for one another. Men committed shameful acts with other men, and received in themselves the due penalty for their error.
28 Furthermore, just as they did not think it worthwhile to retain the knowledge of God, so God gave them over to a depraved mind, so that they do what ought not to be done. 29 They have become filled with every kind of wickedness, evil, greed and depravity. They are full of envy, murder, strife, deceit and malice. They are gossips, 30 slanderers, God-haters, insolent, arrogant and boastful; they invent ways of doing evil; they disobey their parents; 31 they have no understanding, no fidelity, no love, no mercy.
Ummm. . . .so yea that is one reason why I believe homosexuality is wrong. . .because the bible says so. Might I suggest that your first mistake is being religious, Christianity is not meant to be a religion, it is a faith that Jesus died for you sins and rose again. Nothing beyond that matters, the way we live our lives is meant to be a honest joyful response to the Love God shows to us.