"I don't know, and neither do you"

I don't know if there are diamonds hidden within the walls of my house, but pretending it's true is going to result in a lot of damage.

The default position is to say "I'm not convinced there are diamonds in my walls" until someone proves me wrong.

I may not "know", but I'm almost certainly right. I'm also very confident that all of the religions I know about are wrong. I feel justified to say I know that, even though, semantically, that's technically incorrect.