I found the stories linked below pretty interesting. Apparently, there are many atheists out there who do like church, they just don’t like the idea of a god. So now, some of them have started forming congregations to preach their gospel of god-less life. It is fascinating because it shows that there really is a positive social and moral component to religious life, and that these atheists are trying to recreate that good that they see in traditional religious groups while forgoing what they see as a superstitious belief in a magical supreme being in the sky.
Ultimately, what do they preach? It sounds like they preach philosophies that aim at being good to others and living life to its fullest.
Personally, I applaud those who are striving to find and preach principles of goodness. In the second article linked to below, it discusses Pope Francis and his recent statement saying that atheists are good if they do good. Jesus Christ taught that you will know a person by their fruits, or in other words, their works. If their works are good, then they are a good person. Why should it matter if they believe in a god if they are still doing the work of God?
The only danger I see with this practice is if an atheist church is preaching principles that lead away from doing good. God-fearing religions are also under this maxim, though, that the preaching of evil results in evil. For me, I believe in Jesus Christ as the Son of God and Redeemer of the world. But if I were to attend a church that professes to be of Christ and they teach hateful or destructive philosophies, then I should cease to attend because you are what you eat. The words we consume become our moral fiber.
Being good is often a community based effort. It is difficult to be alone in living righteously. If a community of atheists is seeking to be good and find that gathering as a congregation helps in that righteous lifestyle, then good for them.