Which law banned discrimination based on religious beliefs?

The law that bans discrimination is written in The Bible, which is the letter from God, according to 2 Timothy 3: 16,17, which was given to mankind, so that we can be fully competent, completely equipped for every good work, and we should all be aware of. Acts 17: 26 , reads: " And he made ( God made) out of one man every nation of men to dwell on the entire surface of the earth." Which means that all humans are equal before God.

Acts 10: 34,35 reads that God is not partial, but in every nation the man who fears God and does what is right is acceptable to him.

So to answer your question: The law that banned discrimination is the law based on God's requirements as stated above.