If I were so offended by your post that I went out and slaughtered a bus load of nuns, would it be your fault? Perhaps you should be careful of what you post. You might have blood on your hands.
If I posted it with the intent to offend and infuriate you and to provoke you to violence then morally it would be my fault. If I filled your head with anti-Catholic propaganda and falsehoods then I would be morally responsible for what happened.
There is a huge difference between doing things intentionally and unintended consequences. These consequences were EXACTLY what the phony preacher wanted exactly.