The oldest religions in the world are the ones that are not only okay with gambling, but actually have gods related to them. I know for sure in Chinese Buddhism (which is mixed somehow with Taoism and Hinduism, long story short, Buddha with a lot of gods) there are certain gods you pray to at temples before you gamble.

The same in India if you gamble and have good luck you must pray to Lakshmi, one of the most important gods of all. 2 weeks ago we had Diwali celebrated by a lot of my colleagues and you MUST gamble on the night to impress her.