I never did "come out"
I just asked those hard questions
until no one asked anymore, forty years ago now.

If I had it to do over again, I think I would do the same thing but applying the Socratic method through SE (Street Epistemology)
By politely asking them what they believe and why they believe that, you will reveal they have no compelling reason to believe what they believe both to you and to themselves.

In the process they will figure out you lack belief yourself.

Why come out at all? I can understand coming out as gay for the sake of relationships and having an open lifestyle, but it seems to me that being an atheist isn't so much of a lifestyle as just a refusal to believe in god. You know, I'm gonna recommend a podcast on iTunes called "The Friendly Atheist" where they address this issue better than I can. They have a listener question segment during the last 10 minutes. I think Episodes 205, 207 and 208 can help with your concerns. Just fast forward to that portion of the show.

If they are loving parents and will accept you as you are because of their love for you, then it should be fine. If not, then it'll be a rough or non-existent relationship. I had a good friend with parents who are chose Jesus over their heathen, grown children, so it's a barely acknowledging you're there type of relationship. The parents figure it's ok for them not to be in their son's life because Jesus loves them. Horrible justification, but they are good with it.

‘’To thine own self be true, and it must follow, as the night the day, thou canst not then be false to any man.’’ - William Shakespeare

I think you have to just do it and let them react. There may be casualties but it will be there doing, not yours.

I had to come out as an Atheist and a Heterosexual. My Parents just assumed I was gay.

With the Atheist thing I just asked them why god did this or that and looked confused.

Why did God have King David’s innocent Wives publicly raped for his sexual indiscretions?

Why did God kill all the innocent first borns of Egypt?

Why does god tell us how to sell your daughter as a sex slave. I want a new Playstation, how much do you think god thinks my sister is worth?

As a gay person, coming out in any context can be so freeing! Omission is just as restricting as lying. It's hard to know the right words and no matter how you plan it, it will go completely different. Practice what you want to say, repeat the important points in your head and make sure you don't turn it into a blame statement.
It feels good. Like. Insanely wonderful.
Best of luck!

I don't envy your conundrum, but as the saying goes, where there is a problem, there is an opportunity. In this case, it's an opportunity to get through this with your integrity intact. I would take baby steps (as opposed to an alcohol fueled rightous rant), and avoid confrontation, as it is very unlikely you are going to change your relative's minds. For example, I keep my head low and mouth shut when others at the table say grace to their make believe sky god... it will only create lasting animosity and unnecessary conflict if you bite all the bait offered. However, if your have children of your own, I would certainly draw the line before allowing others to fill their heads with archaic nonsense.

My telling my parents I was atheist was inpart so they would nto have any amunition to throw at me because I wa more coming out to them as being gay. I thought through several scenerios and decided to write a letter (this was before email), because face to face I ws pretty sure things might be said tht could nto be taken back.

You know your family best, think through your options and chose the path tht will most likely brign about results you hope for.

I did pretty well. Almost everyone reacted as i had thought they would. I just got it wrogn with my two brothers. I thought my oldest nonreligious brother woudl be mroe acepting, and my middle religious brother woudl nto be, but it ws the other way round. Still myparents nd my three sisters reacted pretty much as I had thought they woudl with the plans I made.

I just told my aunt and uncle. I was upfront about it and they understood. I won't go to church with them anymore. It's been 2 years that way.

My advice is not to "come out" per se. You risk breaking some important family ties.
My approach has been to honestly, as tactfully as possible, tackle topics as they come up, naturally, in conversation.
My family is "getting it" over time. I don't think it's important to label it. At this point, I suspect they think I am in some kind of skeptical period and burned out on church. Cool. Nobody is giving me shit over it.
I have had the opportunity, now and then, to challenge certain views.
That's where I'm at, at this time. Whether I like it or not, my family is a Christian family. They are very important to me. I love them and don't want to compromise unnecessarily some of the cool stuff that transpires between all of us.
Where I have to dig in the most, to my mind, is to not allow my young son to be indoctrinated. That has been the cause of some rather good discussion.
My family is fundamentalist, but can be reasonable, topic by topic.
I hope that helps! GL

If your family can't except you for who you are when you do except them why would you want them in your life anyway? just be honest if asked.

Take Nikes advice, just do it !

I would go slow and when certain beliefs that you hold different come up, state your position clearly. It is more important that you live as you are, even though it would be nice to have their acceptance. Maybe that will happen and maybe not! People that hold strong religious beliefs are not easily moved! Best of luck...

When I came out as an atheist to my parents, My parents main concern was that I'd be a negative influence on my younger siblings, who all hadn't yet reached their teenage years while I was then 18. My parent's are also not fundamentalist, and are even otherwise very principled and reasonable people. All it took was for me to show that I was a good and principled person myself for their fears to be assuaged.

If your family are truly reasonable and not too far of the deep end with religion, then I'm sure they will be unable to shake the rational conclusion that they have nothing to fear from you in regards to their children. However, I'd say you should respect (and assume) any wishes from your brother to keep the subject of your atheism off of the minds of your nephews. In the short run, it may be best to avoid being the source of religious tension in their household, as your positive relationships with your brother and his wife are what grant you access to your beloved nephews.

Lastly, from what I understand, the term "agnostic" is generally recieved better than "atheist," so that may help ease the reveal.

Do it in a manner that is respectful, tell them that they have done a good job in raisu=ing you as a good person and you love them and respect that they are intitled to their own beliefs but that those are not your beliefs and that they need to respect you and yours as you respect them and theirs. Good Luck.

Why do you feel the need to "come out"? By the way, I hate this phrase being used for atheists as it is stolen from the gay community and the two aren't even close to being on the same level of importance.

Why do you want to do this, exactly? Making a big announcement is pretty confrontational, at best. Perhaps just fading from the religious stuff and explaining Briefly one-on-one if/ when asked?
IMO it is nobody's business what Anybody believes......

You can continue to be an atheist without telling anyone about it.
I didn't have to come out myself but I've heard some bad tales of some who have to religious families.

Consider carefully what the consequences could be and if they are worth enduring if you open up about your non-belief.

Hmmm..hard call. Depends on your relationship with them, I suppose. I am not known for keeping things under wraps; after I realized I was a partial transmale, I came out to my family in a casual, brief group email.

This might work for some. That way, people can react and get over their outrage before you see them next, and/or because the message is so casual and brief, it is less threatening. No big emotional, condemning confrontation-just a casual mention.

An example: "After comparing religions and old manuscripts like the Sumerian texts, which has the same Bible stories but was written 2000 years before the Bible, I no longer believe the way I did. People are free to believe what they wish, but I no longer do."

Before you say anything to anyone, please make sure you're emotionally ready for the reactions you're probably going to get. Coming out may result in losing contact with family members, including your nephews. It is entirely possible, and pretty likely, that your brother and his wife might cut you off from their children. At least, initially.
Only you can decide when and where to tell people.
Good luck to you. This community is here to help, regardless of what you decide to do, and when.
Welcome to the asylum. Enjoy your stay.