You're right. Manson did screw himself. But the problem wasn't what most think. Of course he was nuts, but he was nuts because he actually lived what he believed. He really believed that because evolution is true, there is no such thing as right or wrong. He did what he wanted, which happened to be killing a bunch of folks for their money or stuff.
The rest of the world says they believe in evolution, but don't actually live like they do. I'm really not sure who is the more insane; Manson because he believed it and lived that way, or the rest of the world who say they believe it, but don't live it.
I don't know much about Stephen Pinker, but I did take the time to Google him. What I noticed is that, like other "scientists," he does a lot of describing, but not much explaining. Very few scientists, especially those in the behavioral sciences, could talk at all if they had to eliminate from their vocabularies words like 'may,' 'might,' 'could,' and 'possibly.'
I've noticed, I think, that many non-Christians complain about Christians because they don't use those kinds of words when they are explaining the world we live in. They just make authoritative statements, which in our relativistic (almost) world often comes across as really arrogant. The problem is that if relativism is true, then none of their reactions make any sense.
There were a number of people present at Jesus' resurrection. The Roman soldiers were there on the scene when it actually happened. They told the Jews, who bribed them to keep it all hush hush. Then the Jew lied about it and said someone stole the body. Next a bunch of women saw Jesus alive. Finally, Jesus appeared to the Apostles and then over 500 other folks (most of whom died because they claimed to have seen him risen). As evidence we have the four Gospels and a changed world. If all we had were the four Gospels, it would still be more evidence than we have for Plato's existence and a bunch of other ancient things no one argues about.
I hope this helps.