You don’t need to kill L. Ron Hubbard. Just doing the other stuff would change history so drastically that he’d never have been born. It would also change modern Christianity so much that you might not even recognize what it becomes… if it even still exists, and hasn’t been replaced by a newer, more aggressive Abrahamic religion with a new prophet. Nor would it stop new religions from forming in reaction to whatever it becomes. And if people still spoke English anywhere, you probably wouldn’t understand it very well. For all you know, humanity might end up still living in castles in 2020, or they might have nuked themselves out of existence in 1890.
This is assuming timelines aren’t self-correcting, in which case this will end up doing virtually nothing. And that the past isn’t fixed, so that you can’t do anything you haven’t already done.