Julia, I have a very simple and easy solution to your problem.
Move out of your mother in law house.
You might be a wonderful mother and wife, I do not doubt that for a moment, but you and your husband have to be responsible for you and your family, not his mother.
I do not think that your religion or where you came from have anything to do with what is happening in your household. That is not the real problem. Being under her roof is the problem.
Have a discussion with your husband, and figure out a plan. Focus your energy on your family. Live, prosper and be happy, even if it means you will have less money at first. The happiness you create in your household will be yours, don't let anybody tamper with it.
After all, you live in America now. People here trust themselves and depend on their own talents and hard work.
Good luck to you Julia. Embrace the beauty of this country, the self reliance, the opportunity, the hard work.
If your circumstances are such that you absolutely can not move out, than you have to live by her rules. You have no right to complain. It is her house, and she has every right to sing or pray as she pleases. It is her house. You have to treat her with respect.