Complex sentence: His distrust of both Superman and Luthor leads him to form the Outsiders, objecting both the League and the MLF's plans for making a better world, feeling mankind should be able to make its own decisions and mistakes.
Split into simpler sentences: His distrust of both Superman and Luthor leads him to form the Outsiders. He objects to both the League and the MLF's plans for making a better world, feeling mankind should be able to make its own decisions and mistakes.