That's how it is with religious extremists.
Not always. It's almost always like that with violent extremists (of any kind), but there are many peaceful religions that when taken to an extreme, do not result in violence.
Extreme Buddhists will do things like refuse to harm earthworms by digging foundations.
That is taking their religion to an irrational extreme, but no deaths. Going the opposite way actually.
I fear no Jainist, no matter how extreme their devotion. I feel safe in any devout Sikh neighbourhood.
Indian, Native American, Japanese, and many others worship nonviolent deities and concepts.
The overwhelming majority of religious violence revolves around the Abrahamic religions, and their inability to play well with others.
That is not coincidence. Violent teaching of violent ideology results in violent people.
That's how it is with religious extremists. They hate everyone except their sub-sub-sub-group, but they might ally up with others for a while.