Your friend is likely similar in beliefs as a lot of gays. Probably outnumbering the radical gays but a whole lot quieter. The radicals are out there in our (non-gay community) faces, and public schools, striving for "rights" and screaming to be left alone at the same time. In both I think there is a strong desire to be accepted with different ideas on how to achieve acceptance.
Frankly I don't think gays are being hypocritical for wanting gay marriage legal. For some anyway. Others I'm certain are motivated for political reasons. I don't think their lifestyle makes marriage very workable, however. The problem here is not entirely about gay marriage; its that our American society is on a fast track of moral decline that has allowed sin(s)to become acceptable in our eyes. We've accepted divorce and adultry and then when gays decide they want to marry we suddenly become 'moral'? I'd like to ask where we all were when divorce was not the norm or when having a child out of wedlock was shameful?
If the word 'sin' is offense to you or anyone else then lets use the word 'immorality'. No matter what word we choose to describe this rotten, stinking decline in our society those words require a point of reference.
The Church has failed in its call to be a 'light' and 'salt' in the world. They somehow think its their job to condemn; or, equally disturbing, accept what is unacceptable in God's eyes. Referencing the immorality not the person.
As for your comment on religious 'credence', that's your perogative but it is also a Christians' perogative to hold the belief that on God's Word alone sin is sin and not to be embraced as normal. Notice I'm saying the sin is not to be accepted as normal; not the person.