Is religion inherently violent? Are religious people more violent than non-religious people? I don't think so. For many of us, myself included, our faith in God and following after Jesus has worked to purge violence out of us. (Still more to come...)
Is atheism inherently violent? I think so. Since if one follows the logic of atheism-as-metaphysical-naturalism, then morality doesn't even exist. As Nietzsche the atheist knew, humans invent morality for their own self-preservation. It is important to know that the greatest moral atrocities of the last century were perpetrated by atheists - see here.
On atheism-as-naturalism there is no place for human free will. To acknowledge this provides incentive for bad behavior. Alfred Mele writes:
"There’s evidence that lowering people’s confidence in the existence of free will increases bad behavior. In one study (Vohs and Schooler 2008), people who read passages in which scientists deny that free will exists are more likely to cheat on a subsequent task. In another experiment (Baumeister et al. 2009), college students presented with a series of sentences denying the existence of free will proceeded to behave more aggressively than a control group: they served larger amounts of spicy salsa to people who said they dislike spicy food, despite being told these people had to eat everything on their plates." (Mele, Free: Why Science Hasn't Disproved Free Will, pp. 4-5. Oxford University Press.)
Growing up, I was not an especially violent child. I didn't get into fights. I've only hit someone once, when I was about eight years old. I hit a kid who was bullying me. I didn't hurt him. But he hurt me, having hit me very hard.
Why are religious people portrayed by some as inherently violent? Miroslav Volf calls this "the self-inflation of the negative, the tendency of the evil to loom larger than the comparatively much more prevalent good." (Volf, A Public Faith, Kindle Locations 946-947) It only takes one cockroach in your food to turn a delicious meal into an abomination. Our media frenzy-feeds off violence and evil. One televangelist who steals people's money spoils them all, in the eyes of irrational people.
"One can easily show that the majority of Christians (and the majority of religious folks in general) are nonviolent citizens, peace lovers, peacemakers, some even peace activists—and are such precisely out of religious reasons. The purveyors of violence who seek religious legitimation are statistically a small minority among Christians (as they are among other religions as well)." (Ib., Kindle Locations 939-942)
My experience with a few thousand Christian leaders over the past 40 years, as I have been privileged to instruct them and read their spiritual journals, shows me that the vast majority of them are not in ministry to make money; are great servants of other people; are in touch with the violence and rubbish in their own souls; and pray for increased love and compassion towards others.
None of us are perfect. Those of us who follow Jesus are influenced by his nonviolent alternative. To follow Jesus is to have the human heart transformed from violence into peace.