Why are some moderate religious afraid of atheism?

[Silver]

It goes both ways: a religious person might feel threatened mentally when an atheist tries to "convert them"; and atheist person might also feel threatened when a religious person tries to convert them.

That goes for everything in life; btw. Humans usually reject change. It's not a specific of the religious.

Bolded: I am not aware of an atheist movement geared toward missions and ministry; that's more of a primitive theistic problem.