I’m not arguing that secular people (or, indeed, nations) can’t be evil. While you bring up China, though, it’s a bit of a myth that they’re not religious; approximately 80% of the Chinese population practise cults of gods and ancestors or belong to folk religious movements.
My point was that it’s a bit odd to pick the US as your example of a secular country when it is at the moment de facto Christian.
With regards to Bush being ‘as religious as Trump’, that’s just simply not true. He’s a pretty devout Christian, and has put it in a prominent position in all his campaign rhetoric, more than any other president of this generation. If you just Google George W Bush religion you’ll find plenty of news articles from a variety of sources saying that (e.g. this or this).
Stewart Lee did it too, but I think it only works when the audience is ‘in’ on the joke – that is, they are expected to realise that the insult to the audience is itself a joke, rather than the comic actually meaning it.