It's hard to show that religion causes wars - they always have multiple causes. The crusades, even, do as well. This is an interesting academic book arguing this thesis: https://www.amazon.com/Myth-Religious-Violence-Ideology-Conflict-ebook/dp/B0052566Q0
Is it tied together, though? Indubitably. Does religion make wars more likely, or worse? Very likely yes.
The inquisition and witch hunts are much more clearly religious in nature, though.