What kind of evidence for souls, spirits or this elusive anything exists?I mean the belief that nothing beyond physical matter exists. So no souls or spirits or anything.
How or why is anyone expected to notice their existence, if they happen to exist?
What, if anything, is supposed to be in any way different in a world where they exist while contrasted from one where they do not?
Ultimately, theism (defined as the willingness to believe in the existence of deities) is both meaningless in and of itself (what is supposed to be called a god, and why?) and demonstrably a matter of aesthetical preference as opposed to rational or epistemological analysis. So is animism, which is more properly connected to conceptions of souls and spirits.
Atheism deals with the world as it shows itself to be in more rational terms than theism, and is a lot less prone to misguide or to waste attention, effort, or emotional investiment.
Theism is a personal inclination due to very personal factors, and should expect no acknowledgement nor cooperation from outside the person proper. Among other reasons, because it is dicey at best to assume that any two people attribute the names "god" and "deity" to particularly similar real or fictional entities. It is one of the vaguest, less defined ideas in the whole history of humanity.
It is not quite the same as teaching disregard for reality in order to protect fantasy. But it comes real close and often crosses that line without any regard to eventually learning better.