Overconfidence in your ability to judge whether by others are right just by listening to their arguments has lead a lot of very smart people into a lot of very weird, and sadly wrong, beliefs. Particularly since anyone who has a weird belief quickly learns facts that most people don't know, and quickly learns seemingly sound arguments that are mostly (but not entirely!) true.

I suggest picking up a copy of Why People Believe Weird Things. It may be eye-opening for you.