Marriage should be defined as the union of a man and woman under God.
You can give the same or similiar rights to Gays under government law, but it does not have to be called Marriage. I believe the term "Union" will work.
If you believe in God, then you understand homosexual lifestyle is a sin, thus, you would not pursue Marriage with the same sex under God.
Your born that way? Yea, I am born to have sex with every woman in Indy. But I don't, because under God, that is a sin. Thus, I am married and love only one person, my wife.
Just My Opinion