This is a classic slippery slope fallacy. Millions of religious people exist from all sorts of ideological spectrums. The vast, vast majority are not evil and don't do bad things.

The extremism present in religious people is also apparent and present in atheists, agnostics, or whatever generic belief system you can think of. Religion by itself doesn't cause extremism: ad hominems, whataboutisms, and disinformation causes extremism. Constantly comparing yourself to an enemy and convincing yourself you are in the absolute right causes extremism. Sure, you see some 'religious' people going crazy and shooting up places. They also have manifestos that are completely detached from reality in a way that reeks of far-right propaganda and disinformation, and never any real coherence or thought given to the religious teachings they supposedly follow (if they mention their religious texts at all, it's often cherry-picking or outright incorrect).

We should not try to fix the issues of mental health that plague a lot of countries by going after religion. If anything, that would only backfire by virtue of validating any persecution complex religious people might have. We should instead focus on providing affordable mental healthcare that is easily, immediately accessible and normalized for the wider population, as well as providing clear sources of valid information and having any questionable sources that construe facts and claim to not be news sources in lawsuits or elsewhere be forced to clearly denote themselves as not news regularly.