this is still a focal point of debate for the united states, and, with religious grounding being the primary cause, it's important for non-religious and fundamentalist religious people alike to read this article. there's a lot of excellent points worth considering (and many of them point to some much deeper questions about biblical scholarship and literalist interpretations, but that's another thread for another time.
it's a good read and not terribly long.
I have to disagree with this to an extent. It depends on the parameters you set but the way I read Romans 1:26-27 it certainly seems like homosexual acts are sinful.
24 Therefore God gave them over in the sinful desires of their hearts to sexual impurity for the degrading of their bodies with one another. 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. 32 Although they know God’s righteous decree that those who do such things deserve death, they not only continue to do these very things but also approve of those who practice them.
edit: Maybe I should read more than just the OP before responding. looks like someone already brought this up.