We shouldn't think of science as a better replacement for religion. It's a different thing entirely; if we start worshipping rationalism, we've just made ourselves the gods of a new religion.
I think their point was that we inherently start worshipping ourselves once we begin to think that we are the source of empirical truth and rationality that our gods used to be.
My point is that many people reject the idea of godhood altogether, and the concept of worship is akin to voluntary slavery. Some people never had any gods at all.
Just because a group of people does something frequently, does not make it a requirement or even an expectation of the whole.
Rationalism can lead to a cult mentality. It's happened before. Of course, you could say that this isn't "true rationalism", but you have to ask yourself if you're actually practicing rational thinking or just fetishizing the trappings of rationalism. I think that this means that skepticism is just as important as rationalism.