"The enemy of my enemy is my friend" - a really really bad aphorism. It was unlucky for the Irish, unlucky for the American Native tribes, and pretty much anyone else who ever used it.

"We only use x (really tiny) percentage of our brain cells" - obviously wrong. We have all that gray matter because biology and the process of evolution determined we need them, they are expensive to maintain. (And currently we use them not at all!)

"This will hurt me more than it hurts you!" When has this ever been true?

"We can never comprehend infinitude" Actually, infinity is a human concept, so it has already been comprehended. It's just large numbers of things we can't usually keep in the mind at the same time.