Religions are the problem. The unquestioning loyalty and assumed goodness is a breeding ground for heinous thoughts and actions. He was religious in this sense.
or
Violent acts like this aren’t religious, and those who claim they are religious and still do this are co-opting the word “religious” which should connote care for others. He was not religious in this sense.
Either way, my comment “religious” brings to light that the use of this word is irrelevant at best but more likely problematic and misleading.
who took the photos