To an extent, I agree with him. I would rather have evangelical Christians (and everyone else, for that matter) support marriage equality even if it takes a while for them to get there.
But only on a few conditions.
They can never say that they were on the right side of the argument when it mattered.
They can never say they helped steer our country in the right direction.
They have to admit they were part of the problem, and that they either fought hard to take away civil rights from LGBT people or (in the case of silent Christians) prevent them from getting those rights in the first place, and that they gave money to churches that were openly and proudly intolerant of homosexuality, and that they stayed silent when we needed their voices the most, and that they held on to their homophobia because their religion taught them to do so.
If they’ll admit to those things, I don’t care when they come around on this issue.
Yes, there are evangelical Christians who have always been openly supportive of LGBT rights, and I can’t express my gratitude enough. But their support came in spite of their churches, not because of them. While a few Christians denominations supported equal rights long ago, there’s no reason to think they shifted the paradigm on their own.
History will — and must — remember Christianity, certainly evangelical Christianity, for being an obstacle to LGBT equality. We cannot allow for any historical revisionism on that even after the tides turn.