If your neighbor told the neighborhood for years that he wanted to kill you and your family, and he made every attempt to do so but had not succeed in completing the task, would you still say that his mission did not matter if your neighbors rebuked you for acting on that knowledge? No, I would grab my Berreta .40 and pop a cap in his brain can. I wouldn't however, then tell everyone that I needed to do the same thing to his entire family and everyone who practiced his religion.
You said missions don't matter, actions do. I asked you if you would feel justified on acting on the mission of a neighbor, and you say
I would grab my Berreta .40 and pop a cap in his brain can. I rest my case.