What religion do Egyptians study?

Answer 1

In modern day Egypt, religion is endorsed by law and controls many aspects of social life. About 90% of the population is Muslim, 10% Christian. Any new legislation must at least implicitly agree with Islamic Law.

Answer 2

You should be more specific when asking question, I am assuming you me in Biblical times.

They worshiped the sun god Re (for one)

The rise of Christianity in the Roman Empire caused an end to the worship of Ra by the citizens of Egypt, (Ra's popularity suddenly died out).