Is bank interest permissible or impermissible? And why?

The bank's profits are forbidden because they are the essence of usury, which Allah and His Messenger have prohibited. Allah the Almighty says: "O you who have believed, fear Allah and give up what remains [due to you] of interest, if you should be believers. And if you do not, then be informed of a war [against you] from Allah and His Messenger." The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses, and he said: "They are all equal."