God actually never said anything of the sort. The quote used by Leviticus is under heavy debate and more accurately translates that men can't own men like they own women (aka as little house slaves). The term "homosexual" wasn't actually coined until the 19th century. [link]
I have no strong feelings one way or other, but I am leaning towards allowing gay couples to marriage, since marriage is a social institution before a religious one, and we should interfere with people private affairs
We are all equal and deserve to be loved the way we want to be loved. Your attitude towards something you don't accept or wouldn't want to accept shouldn't be governed by religion but by how you want to be treated by others who don't agree with you and your beliefs.
What I am saying is that I wouldn't worry much about what god thinks. There is never a definite proof that god actually said anything about any issue since there are many supposedly gods as there are many religion. You never actually know, so why restrict your beliefs down to what has been written in a book that has been altered many times throughout the ages? Just live and let live, bro.
Here is proof of what God has said about the "issue". Read it over a few times to understand it.
21 For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. 22 Although they claimed to be wise, they became fools 23 and exchanged the glory of the immortal God for images made to look like a mortal human being and birds and animals and reptiles.
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.
It boils down to "God made Adam & Eve, not Adam and Steve". The way I see it, God made man in his image, and made woman from man, with the intent of them being together. It was a highly symbolic and meaningful act, and anything that deviates from that is a corruption of the image of God and his intent for our relationships. I think that God also gives us certain situational allowances (given how we messed up so much), like outlines for divorce, allowing polygamy, etc... but he also wouldn't encourage gay marriage, since it's considered sinful in the Bible (just like he didn't encourage divorce or polygamy, he just allowed it since we're screwups).