I am a devout, practicing, traditional Catholic, and I am against Proposition 8.
This might seem like a paradox, and may not be conservative enough or liberal enough depending on your views, but bear with me. The Roman Catholic faith, to which I am a fervent adherent, maintains the following official position on the matter of same-sex relations:
"Basing itself on Sacred Scripture, which presents homosexual acts as acts of grave depravity, tradition has always declared that 'homosexual acts are intrinsically disordered.' They... close the sexual act to the gift of life...Under no circumstances can they be approved...This inclination [however]...constitutes for most of them a trial. They must be accepted with respect, compassion, and sensitivity. Every sign of unjust discrimination in their regard should be avoided."
- Catechism of the Catholic Church, 2357-2358
The Catechism goes on to state that LGBT people are "called to chastity". This is the case because the Catholic Church teaches that sexual activity must be both an expression of eternal love and an act open to procreation. Since same-sex relations cannot be procreative, practicing Catholics are bound not to engage in them. Some Catholic theorists go so far as to say that romantic love cannot exist between two people of the same sex.
I can't disagree with the Church on the point that practicing Catholics cannot engage in homosexual acts without committing a sin. And I believe that any form of sexual activity in which a child cannot be created is also sinful (including masturbatory, oral, anal, or "safe" sex between people of any gender). However, I strongly disagree with the latter point: I have seen many same-sex couples who are more loving than a substantial number of their heterosexual counterparts. While I believe that the Church cannot permit her members to be joined in same-sex marriages, American civil law is, or should be, a completely different ball game.
First of all, what ever happened to separation of Church and state? At the end of the day, I'm glad I live in a nation where not everyone agrees with me. Freedom is what makes this country great. Secondly, since when does a government have a right to declare who its citizens can and can't marry? If John Doe can marry Suzy Smith, why can't Jane Doe marry her? In a democracy, the citizens are supposed to have true sovereignty over their government. So how can we let our political leaders tell us who to love, to honor, and to cherish 'til death do us part? I've always felt that part of the American dream was being able to love whomever you love, without apology. No matter what anyone says, I will never be convinced that love is a choice.
I encourage people to be true to their beliefs, whatever they are, and I especially urge all Catholics to follow the Church's teachings. That said, the matter of your sexuality is very personal. Share it with your partner, your friends, your family, trusted members of the community, your confessor, anyone, everyone, or no one at all if you don't want to. Whomever. But who you love is none of Uncle Sam's gosh darn business.
Some relevant links...
Courage, a Church-approved ministry to LGBT and questioning Catholics
The Trevor Project, a non-religious, non-profit resource for LGBTQ youth