Malachi 3:10: "'Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.'"

Matthew 25: 29-30: "For unto every one that hath shall be given, and he shall have abundance: but from him that hath not shall be taken away even that which he hath. And cast ye the unprofitable servant into outer darkness: there shall be weeping and gnashing of teeth."

The Bible is a pretty big book. There's something in it to justify just about anything you want to believe.

That does sometimes involve tapdancing around the plain meaning of some other parts. That's called "prooftexting", and it's frowned on by serious theologians, but the kind of people who hoard wealth usually aren't serious theologians.

I suspect it's performative. Going to church, praying with others, these are performances. Doing the good deeds is what counts.

But it seems to me like it would be crazy hard to push a camel through a needle. Also, it's one of those things where I think the translation is a bit off. Apparently the word in Aramaic is said like "gamla" which does sound rather like camel, but also meant rope, which makes a lot more sense in context, though still pretty difficult to get through a needle.