If your concept is that individual Republicans can't evolve on the subject matter, you have to then explain all of the Democrats who opposed harshly and are now supporting equality. Biden voted for DOMA and said in his VP debate that he agreed with Sarah Palin on marriage equality. Obama used to say 'I'm a Christian so I believe marriage is for one man and one woman' then he'd add words about Sanctity and who is Sanctified and who God sees as less than worthy, then he'd introduce his 'good friend' Rick Warren who had just given a press conference calling us all pedophiles.
We have several DUers who say they support equality now who previously did not, some of them were raging propagandists constantly slandering gay people. Tons of DUers are comfortable with hearing bigoted trash talk about gay people if it is done by men in silk robes, hell, DU celebrated the elevation of the world's leading anti equality leader, Biden went to honor that man, so there's Biden again.
If your desire is to see no majority rise for equality, then attack those who learn and grow.