Do Christians have a conflict of interest regarding same-sex marriage?

In the Christian Bible, it is clearly stated that homosexuality is prohibited. Three prominent leaders of the Anglican , Catholic and Greek Orthodox Churches have released a letter this week to all their parishioners urging them to reject same sex marriage. Should Christians question the Bible in terms of homosexuality considering it has been scientifically proven that some elements, of it have been proven wrong? (such as Noah's flood) Should Christians be exempt from the issue of same-sex marriage because of their conflict of i interest? originating from their religious orientation?
Read More
en.wikipedia.org/wiki/Ellen_DeGeneres
en.wikipedia.org/wiki/Civil_union
en.wikipedia.org/wiki/Lady_Gaga
www.huffingtonpost.com/2011/06/10/lady-gaga-gay-rights-rome-rally-born-this-way_n_875448.html
www.huffingtonpost.com/2011/12/06/hillary-clinton-gay-rights-speech-geneva_n_1132392.html