Christians banned it for most of the history of Christianity. Starting in the late Middle Ages, the way they'd game the system was by having Jews do the lending at interest, which they were OK doing as long as it was the goyim on the receiving end. Some of the Italian city-states also started doing interest-bearing loans around that time. Then, when Protestantism started, everyone got into the game.

Islam forbids it too. So they've developed slightly different financial mechanisms which in most regards work similarly to interest. The big difference is that lenders have more skin in the game. And for that reason, most Muslim countries that actually ban interest (many ignore the ban) have a problem with systematic underinvestment.

That's the problem with very thick books, you just can't remember everything ...