You've got a lot going on in your question. Some of the facts you describe would not give rise to a legal claim (e.g., implementing a no nepotism policy, and then making an exception for your niece). However, other facts might give rise to a claim (e.g., required prayer at meetings). You may want to consult in person with an employment attorney to get a careful evaluation. Good luck.
My answers to questions posted on AVVO are intended to provide general information only, and are not intended to be legal advice. Employment law issues typically require a careful case-by-case analysis. Consequently, if you feel that you need legal advice, I would encourage you to consult in person with an employment attorney in your area.