It's great to be free from the superstitious thinking I once had, but sometimes wonder how god belief gave me an overall mental safety net. My conclusion is that no matter what belief system you are indoctrinated in, it gives you some sort of security, even if it is fantasy thinking. Maybe its some sort of anxiety cure for the shortness and unfairness of life.
Religion is definitely a kind of "anxiety cure" for people who are unwilling or unable to face the stresses and fears inherent in life without looking to a father figure in the sky for guidance, and ultimately, for a path to eternal salvation, thus in part negating the trepidation people have about death and the dark. Notice that I said "in part" negating that fear. Believers don't seem to spend much time thinking about this, but like it or not and regardless of whether heaven is a real place or not, they will still have to one day face their own mortality like everyone else. As I told Kervin in a response to his post, believers and nonbelievers alike will have to come to grips with the fact that their consciousness will one day end, and whatever else might be out there, their physical lives will be over, and there's no coming back.
This is why so many of us who have left the fold don't want to spend another second following what we feel is a delusion of the highest order. Christians often attempt a "gotcha" moment by asking atheists to consider Pascal's wager. I've addressed Pascal's wager multiple times on this site, but suffice it to say that a person has lost much if he squanders the only physical life he has worshiping a god for which there is scant, if any, proof. They often ask: "What if I'm wrong?" Notwithstanding the fact that I could equally be wrong about Allah and or any of the legions of gods that man has invented through the centuries, if I am right that religion is a waste of time and resources, I am free to spend all of my Sunday mornings and the rest of my time on other endeavors that matter to me, learning new things or making memories with friends. Believers really only have one thing to try to convince nonbelievers to return to the fold, and that is fear, the one consistent bedrock element of all religions.
Believers also attempt to convince atheists with this effusion: That life without God is meaningless, and since meaningless is bad, belief must be good. First, this assumes that God — here I am referring to the god of the Bible — is the originator of all morals and thus is the only being who can bestow us with purpose. But as far as I can tell, the purpose that God supposedly gives us humans is almost exclusively theological in nature. Our higher purposes according to scripture: Spread the Gospel to the ends of the earth, win converts for Jesus and worship God. Readers of Rick Warren's, "The Purpose Driven Life," learned that Warren had been given a message from on high: That the five purposes for humanity (Read: Christians) were evangelism, discipleship, ministry, worship and fellowship. If you notice, however, ministering to the flock and the community is the only one that could possibly be construed to mean that we should work to make the world a better place. Christianity's notion of ministry in the community is only partly about helping the needy or ministering to the community. That would be the second goal ... or third or fourth. The primary objective is to reach people for Jesus, and if believers have to roll up their sleeves and do some real work to achieve the primary objective, so be it. This is the disingenuous and skewed notion of purpose that emits from the church. As such, I don't necessarily know what is meant when someone is concerned about losing their purpose for life when they leave the church. The only purpose the church offers is a thinly-veiled nod to helping the community or serving needy people overseas, all the while carrying along a Bible in case they get to tell the story of Jesus to some unwitting orphan, ESL student or African villager.
So nonbelievers, then, shouldn't despair that they have no purpose. Atheists are free from the kind of phony life purposes offered by the church and can create individualized purposes for themselves through philanthropy, mission work without the proselytizing, community projects, etc., and they can truly give back to their communities and make the world a better place than they left it. This is purpose without religion.