Sherkat performed the analysis on the GSS data following the publication of his 2010 paper, "Religion, politics, and support for same-sex marriage in the United States, 1988–2008," published in Social Science Research. That paper concluded (as the above data through 2008 showed) that public opinion was indeed trending upward for support for same-sex marriage and downward for opposition, and noted, "Our findings suggest that in a little over a decade the majority of Americans will support the legalization of same-sex marriage." While the 2010 data doesn't show an over-50% majority, it does show, far more quickly than Sherkat expected, support outpacing opposition.The data indicate that nearly everyone is modernizing except "sectarian PRotestants" and Republicans. If you identify strongly as a conservative Christian or Republican, you disapprove.
If you look at the data for inter-racial marriage, even today about 20% of Americans disapprove. I am going to bet that you will never, ever convert that rump of conservative evangelical Republicans to support same sex marriage.
The question is, will we put the rights of the minority, and the approval on the majority, aside for the views of this group?