I honestly don't know if you are being intentional about your incredible bias right now. Yes there are shotguns and revolvers all over Europe. There are literally orders of magnitude LESS shotguns and revolvers all over Europe compared the US. Are you capable of understanding how this relates to fewer mass shootings?
Another incredibly easy point to refute. Europe is significantly less religious and more liberal than the US. According to your incredibly backwards theory, Europe should have more shootings.
You have a seriously problem in coming up with your hypothesis and disregarding all facts.
And the middle East is exponentially more religious than Europe or the United States. Violence there abounds, so you make a reasonable point. I don't like it, but you are correct. My sensibilities tell me that Christianity is anti-violent in nature so that's probably the natural counterpoint. At the same time, communist Russia and socialist China are decidedly anti-religion and they have killed upwards of 100 million people. Seems to me that religion or the lack thereof may not be the common factor.