How do I deal with a religious family as an atheist?

Extend them the same level of respect that you want in return. That is the best approach to dealing with anyone who has different ideas than you in general.

Respect is the key to everything and as long as you respect their religious beliefs, you should expect the same from them. If they are being harsh on you about this matter, you may try to avoid talking to them about it, but if you are determined to make them accept it, remind them that being an atheist doesn't mean you are going to be a bad person.

Growing up as an atheist in a religious family and attending a small religious school for 13 years of my life, I know how difficult it can be. Your family might not understand how you don't believe in a "higher being," or whatever it is that they believe in, but others do and that's important to remember. You have to learn to be tolerant of your family and their religion, and hopefully they can do the same to you.

It's better to let that family know that you are not against any religion or it's traditions ,but you never and will never perform or attend the religious ceremony or prayer, it's your personal belief, let them know that there is no hate but it is like you always been as a person, convey them politely, showing all respect for them,

Be who you are. My grandpa was married to a heavy Catholic minded woman and they've been married for about 65 years of marriage. Don't subject yourself to have to be religious because your family is or think you're not holy or what have you. It's up to you and all and there's nothing wrong with it either.

Understand that it's okay to not have the same beliefs. The main thing you guys need to have in common, is love & respect for each other!

You should respect their religion and ask kindly to them to respect your atheism. You should tell your family they should respect your point of view,

Respect is the keyword here. If your family can accept and tolerate your beliefs then you too, should have the capacity and depth to accept your family as how they choose to be. If your family cannot accept you as an atheist then very politely , sincerly and earnestly speak to them about how much you respect their values and would not do anything to harm or hurt their beliefs. Just as much as you love them for what they are, ask them to slowly accept and love you for what you are.

Don't try to push them to not believe and don't let them force you to believe in something you don't. If they like you then they should be able to get over your opinions without a big deal. Trust me, I've been there.

Ask them kindly to respect your beliefs and respect theirs in return. Everyone is free to believe in what they want.