Spiritual reasons for killing others comprise a portion of all of the reasons people have for killing each other, but hardly all of the reasons. Money, power, and territory are also very common reasons people kill other people. And they employ science to help them do it. So let's not be pointing fingers in only one direction when it comes to that sort of thing.

Nuclear weaponry, in my opinion one of the most horrific, and certainly the most potentially destructive of all earthly creations, was not created by people on a religious mission. It was created by scientists for reasons that have nothing whatever to do with spirituality. Sometimes when people don't realize they have a soul, they operate with less concern for any damage they might do to it through the way they behave while in the physical body.

These kinds of arguments can cut both ways.