I just say I'm not religious. Saves the confrontational judgment. In this culture, you're still judged as immoral if you don't believe in their myths. But, it is getting better. The younger generation seems to be more objective.

I only bring it up if I am asked or if their is an activity I am being asked to join in that involves religion. When I do need to tell someone, I am straight up to them and try very hard to be positive and not show my self righteous indignation towards their beliefs.
I am sometimes asked to pray for someone. I tell them to pray for themselves. Sometimes, I see a look of frustration, sometimes confusion. I try not to get into the discussion. I'm not going to change anyone's mind.

I tend to tell people that if there is a God, we will find out soon enough. Might also point out that there are over 3000 Gods worshiped on the planet, so in point of fact, they only believe in one more God than I do. A bit of humour thrown in doesn't hurt either.

I was born Jewish but I call myself a Free-thinker or an Agnostic. In other words a Don't Know!

I don't tell people my beliefs, I just ask them questions about theirs. The longer they explain, the more they begin to question them. I sure question mine!

I don't generally engage with religious people about my beliefs unless they become provocative or smug, then I have a 'both barrels' approach. I think for the most part that religious people are just struggling along like the rest of us and don't seek to be confrontative. For those that do, well, it's open season all year round and I have a figurative 12 gauge science repeating automatic rimfire... 8)

I tell one and all stick with the commandment, LOVE THE NEIGHBOR AS THY SELF and shut the hell up about all the other bs.......

I usually don't unless they start to get really preachy. Then I tell them and if they push it explain to them why I am. Surprisingly I have had some great philosophical conversations with a few of the more open minded types and have gotten them to look more closely at the hypocrisy of many believers. The ones who are shocked and can't accept it are another story. Had some woman throwing holy water on me and turned around and asked her if she saw it boiling? She ran off in a huff. Family members are the hardest. I avoid discussing it as much as possible and have had a pretty successful time telling them that if they bring it up I am leaving. Got up and left in the middle of Thanksgiving dinner once and have never had a problem since.

“Here there comes a practical question which has often troubled me. Whenever I go into a foreign country or a prison or any similar place they always ask me what is my religion.

I never know whether I should say "Agnostic" or whether I should say "Atheist". It is a very difficult question and I daresay that some of you have been troubled by it. As a philosopher, if I were speaking to a purely philosophic audience I should say that I ought to describe myself as an Agnostic, because I do not think that there is a conclusive argument by which one prove that there is not a God.

On the other hand, if I am to convey the right impression to the ordinary man in the street I think I ought to say that I am an Atheist, because when I say that I cannot prove that there is not a God, I ought to add equally that I cannot prove that there are not the Homeric gods.

None of us would seriously consider the possibility that all the gods of Homer really exist, and yet if you were to set to work to give a logical demonstration that Zeus, Hera, Poseidon, and the rest of them did not exist you would find it an awful job. You could not get such proof.

Therefore, in regard to the Olympic gods, speaking to a purely philosophical audience, I would say that I am an Agnostic. But speaking popularly, I think that all of us would say in regard to those gods that we were Atheists. In regard to the Christian God, I should, I think, take exactly the same line. ”

Bertrand Russell

Living in a mostly red state (evangelicals up the wazoo), it's pretty much not brought up unless you like being attacked by 20 or more nonthinkers at a time.
My exwife and former church are about the only ones aware at this point, and I don't have to deal with the nonsense of either one of those now.
MANY people online know (Twitter) but it's in my profile.

I say that I'm not religious. If they seem open minded I'll say that I'm Atheist. I prefer for people to get to know me before I throw a label on myself.

I tend to only say that I am an atheist if I am asked or if a religious person has started insulting atheists.

My (non)beliefs are personal. I'll share them if asked or if someone's trying to force their beliefs on me. And I refer to myself as a non-theist, not an atheist. Purely a personal preference. I'm a deeply spiritual seeker ... I just don't believe in a being god.

Yes I say it but have never had an adverse reaction but hereabout with a Protestant /Catholic divide - no one is really interested in Atheists we are of no account whatsoever though i have heard some people say back to me "ah thats a shame!" I usually just laugh no none has come accross as heavy just mystified.

I say "I'm and Atheist"

I simply inform them that I am not afraid of the dark

Flat out telling them your an atheist is the best way. You have the right to believe in whatever you like. If some people want to believe in fairy tales it's there right and rest of us who believe in non fairy tales that is our right to do so.

Just tell them there is no god and then when they start to argue, ask them to PROVE IT!!

I don't. They either accept me for the hairy weirdo that I am, or they can piss off. My beliefs are personal. Anyone I let into my life respects me, and I return the favor.

I ran into this problem recently with a couple of new friends who are Christians that asked me where I went to church. They had been around me enough to see me as a "good" person and just assumed that I was religious. I decided not to use the word atheist, but instead chose to say that I was an agnostic/freethinker and told them that I was involved in a community group for people of that mindset which was kind of like my version church. They seemed to take it OK, but we did not stay on the subject long. So far they have not said anything else to me about it, though they do talk about god, prayer, and church once in a while. I guess they value my friendship enough not worry about our differences in beliefs.

I usually say "I'm not a believer." or "I don't believe that." I don't feel the need to label myself, and in the part of the fundamentalist Christian backwoods where I live, people expect atheists to have horns and walk around munching on babies.

I just say I'm a follower of Odin of the Norse beliefs, the beliefs of my ancestors.

Call yourself a pastafarian

Only when i was asked i told them that i am an atheist. i think you can say that too if you desire. there is no must . There is no a perfect saying too. i think it is alright to say that you are an atheist if asked.

Even though the word doesn't attract the same degree of prejudice over here in England, I still describe myself as 'non-religious' if the subject comes up. Don't know why... I think I've been following the American atheist scene for so long that I'm almost expecting the same grief as you folks get.

But although my atheism defines me, I never really feel any need to let people know. I think that comes from not feeling hemmed in. The majority of people that I know are atheists or agnostic theists; I think I've only met half a dozen proclaiming Christians in my entire life. Over there it must be very different.