Complex sentence: The Cathars believed that one would be repeatedly reincarnated until one commits to the self-denial of the material world, which meant that a man could be reincarnated as a woman and vise versa, thereby rendering gender completely meaningless.
Split into simpler sentences: The Cathars believed that one would be repeatedly reincarnated until one commits to the self-denial of the material world. This meant that a man could be reincarnated as a woman and vise versa, thereby rendering gender completely meaningless.