Can religion ever be blamed for violence?

Religion is my example, but non-religious ideologies can work for this question.

Often when violence is apparently committed in the name of religion, the defense is “it’s not religion, it’s politics/greed/people. Religion is just an excuse”. But why must religion always be an excuse? Is religion inherently blameless?
How do we determine whether something is a root cause of violence or “just an excuse”?

A non-religious example: When people cite the violence committed under socialist regimes, socialist apologists will fault corruption, ego and greed rather than anything inherent in socialist theory itself. It’s not socialism’s fault, they say, it’s something else. The “it works on paper” defense.

While I understand that most religions in their ideal state cannot be used to justify the kind of violence often committed in their name, I’m not convinced that the religion plays no role in said violence. No, most seemingly religious violence is never wholly religious in origin. Politics, ethnic strife, and power always play a role. But so does religion. To automatically exonerate it of blame doesn’t seem honest. Religions preach peace, but they also preach that violence is sometimes justified.

This is not an “attack religion” thread. Please no snark.