According to "matter-ism," matter is all that exists. The only things that are real are physical things in motion governed by natural law. That story starts, "In the beginning were the particles," or, as one famous person put it, "The cosmos is all that is, or ever was, or ever will be." No God. No souls. No Heaven or Hell. No miracles. No transcendent morality. Just molecules in motion following the patterns of natural law. This is the story that most atheists, most "skeptics," most humanists, and most Marxists believe is true.