It really depends how they interact with you and your family. Sometimes family members can be passive aggressive, direct, or hostile with their beliefs. I find motivational interviewing method works best for starting a conversation with some people, but not others. I find it is all about phrasing with people who live in a strict black and white world.

Level with them. Tell them that you love them and wish to maintain contact with them. But, you also demand that they treat you and your right to believe as you do with dignity and respect. So the onus ion them: Abode by the ground rules, or they will; be responsible for the loss o pf contact.

Well, first of all I don't criticize my family members that are religious. Even if they talk real bullshit, I seldom reply. I just respect them for what they are: Family, people where I have a blood tie with. In general we get along quite well, but as soon as religion comes up, communication stops. I have told them, everyone individually when the subject popped up, that religion is not my thing anymore and that I love them, but that they should not spoil that by bringing the subject up. Giving up religion is my decision and they should respect that. I never started a discussion right or wrong of my decision. Having been open and clear in that way I don't get that resentment and criticism anymore because it has become a non-communication-issue.
On the other hand, family and friends are all individual humans and everyone has its own opinion, temperament and character. If they appear not being able to be respectful towards you, there is no longer a reason to respect them and continuing your contact. In that case, protect yourself and wave goodbye.

If they don't like it, then they have really only two options:
1)either accept it and we can move on.
2) if you are going to make this into some chronic problem and not let it go, then don't talk to me until you've smartened up.

I've had this dispute to a lesser extent with my mom, and her overreaction to it was the last straw for me. Among many other familial problems, this was the tipping point for me when they went so far as to threaten to kick me out when I was younger. At that point its not hard to me to just cut people out of my life that are being problematic. It's an ultimatum I have set for any and all family, if you can't get over benign ideological differences between us, then good bye.

I just know how annoying and problematic this stuff will get if I ever have kids.

Depends how you would balance that with their love if you were ever in trouble. That's where the rubber meets the road. If they'd leave you hanging, then wave good bye... "You can chose your friends, but you can't chose your relatives" as they say.

On the other hand, if they've proven their love to you through thick and thin, go easy on them - they're precious.

Try -- we don't believe the same things but we do have the same values. That worked better than I ever thought it would with my Mom. I also tell people I think life is too short to argue about what you believe in. If they want their religion, fine. But they need to respect you. And they need not to be so insecure in their beliefs that they require you to be just like them in order for them to feel comfortable. Good luck!

I say I love you and I have to be honest with you because I respect you and trust you enough to be truthful with you. This is what I think and why I think that way, if the person is open to talk about it. Some family members are more open, willing, and interested in having a real conversation and able to look at different perspectives. If they are being abusive, don't be abusive back. Just ask to be treated with the same respect that you give them. If they can't give that to you, then you might need to spend some more time with some other people. Let them know you would be glad to talk to them when they can be more respectful. I try to find the common ground I have with people. If you all believe in love one another and you remind them of that, maybe that could set the tone for a compassionate conversation.

Just be polite and say please stop. Will you please stop.... I've made up my mind.

I think you say, hey, if you want to be fooled into believing that fairy tales are real, or if you need that to process the way you size up your life or process your mortality, then you go ahead and live that way. I choose to understand my myself and my roll in the universe in my own way without suspending my disbelief. And i think it's a better way for me, and a better way for humanity when we are free to think, even if it's hard to swim against the current. You go along with the heard if that's what gets you through. I know what's right for me. In other words, you should be strong and proud and confident - make no apologies. One day they will respect you for that.
And until then, if they don't like it, they can lump it!

tell them to leave it at the door or don't be at the door. tell them you will on your part not force your none beliefs on them.

You are not going to be able to have a relationship with them if neither of you don't respect each others beliefs, so, the conversation you need to have with them is one about respect. If both parties can not come to term over this it is not likely you can have much of a relationship. You could lie but, losing respect for yourself will prove to be worse.