Yeah, I get that. But I can't write as intelligently and dispassionately as he does.
But it's funny, because I can relate to what Slate Star Codex is saying. I think his point is that a lot of virtue signaling goes on where progressives aren't really trying to convince conservatives with their arguments, but rather speaking in condemnations and old platitudes that we're aware of, but disagree with.
To engage in signaling is one thing; to engage in debate is another.
His other point is the internecine war that modern atheists, especially on the internet, have brought upon themselves, even with modern progressives. It's a shaming exercise if you believe in God, really, replete with juvenilia and condescension. His question, I think, is what sets this special brand of atheist apart from your average progressive? How did they become black sheep within their own movement when even people like me are sympathetic to their claims? In a way, I understand this. I'm agnostic. But the level of derision with which internet atheists treat their opponents makes nobody sympathetic to their tactics and arguments. In fact, it makes people want to defend religionists and their ilk.
I find myself often in this camp. Sympathetic and agreeing with atheist or agnostic claims; sympathetic and agreeing with religious people that feel like they've been diminished for their beliefs in some way. I'd personally love to form a bridge between the two; but it seems so personally angry on both sides that I usually stay out of it.