Hi, I just joined. I’ve been working on a project like this from various directions for years and know other people who have been working on it from other directions.
The challenge is that until someone can identify every single thing that attracts people to church and replicate it in a secular humanist context, we’re not going to win.
The main obstacle to that is a church comes with a ready made belief structure. Compared to that, I see a lot of people using Atheism (ironically) as a license to believe in anything they want because they don’t believe in a god. To me, to call yourself an Atheist implies a commitment to LEARN facts. Otherwise you’re invoking your own ignorance of facts as a supernatural force that will make your ideas fit together in whatever way you feel they’re supposed to fit together. But I’ve met an awful lot of “Atheists” who haven’t noticed that mistake.
One problem here is that an Atheistic idea-structure depends on a unification of all branches of science and then all humanities by first principles, AND THEN enough people learning it AND believing it. E.O. Wilson’s book Consilience is about that very topic. The unification of all branches of science is only now being completed. The last piece of the puzzle is biology to psychology at the large-scale level.
The other problem here is that Americans have the luxury of being mentally lazy. Weakness is what happens in any ecosystem with a low death rate. In this case it means that Atheistic structure is not being created by any external factor. The result is a lot of diversity, which a lot of people consider to be a good thing. But that also means that natural selection is not acting very strongly on people’s ideas in America, killing ideas that don’t work and preserving those that do. The result is that people are not developing new ideas expeditiously or focusing their efforts toward any improvement over our conditions, because their old ideas are still producing satisfactory results.
I have gotten this critical of American society because I was a volunteer in the War on Terror. Learning to think objectively is one thing, but learning to think objectively under threat of immanent death is something else entirely. People only develop new ideas to the extent that developing new ideas offers perceivable benefit to them. If your living conditions have low perceivable threat, you have low environmental pressure to develop new ideas.
The end result of that as it relates to this discussion, is that, in my experience, when groups of Atheists get together to socialize, essentially nothing productive happens on a scale that can compare to organized religion, The interaction within any social group stabilizes around whatever most people have in common. Among most non-church groups, that lowest common biological denominator is usually sex, drugs, and rock ‘n’ roll. Those are three basic ways to discover new mental states, which can lead to new ways of thinking, but in the absence of strong environmental pressure necessitating new ways of thinking, sex, drugs, and rock ‘n’ roll is just entertainment. When you add in Atheism as a foundation for the social group, it doesn’t go much further, because in the absence of strong environmental pressure now the lowest common denominator becomes a bunch of rich sheltered college educated people hanging out together and feeling smarter than everyone else. People committing themselves to taking action as necessary to seek and destroy every single component of oppressive ideology does not result.
The solution is perfectly simple. Atheism is too much of a stretch for coordinating effective opposition to religion now, but Secular Humanism isn’t. If college educated White people don’t have enough environmental pressure affecting them to develop new ideas expeditiously, look for whoever DOES have enough environmental pressure affecting them. There are lots of people in the world who understand the value of reliable information and who are trying to get better educations in order to achieve their goals. For example, the majority of the human race sees the United States government as the biggest threat to them, so how are people organizing around that idea? There’s no shortage of people in the world who are trying to figure out how to put reliable information to practical use to destroy oppressive ideologies. Lots of people have set up lots of groups whose goals ultimately converge on secular values, just not as directly as the proposal here. So it is possible to work around the challenge that people have pointed out here toward starting something like this up from scratch.
As for debating ideas constructively, it’s harder than it sounds, but some people have figured out how to do it. This is basic social etiquette in the theatre industry, for instance.
Telling a person their ideas are wrong is always an act of aggression, because people need to put ideas to use in order to produce results in life. Inferior ideas means inferior results. That means when you tell someone their ideas are wrong, you’re telling them that you believe, and you’re trying to get them to believe, and you’re showing anyone around you that you believe, that the person’s actions are going to produce inferior results. That means you’re threatening their social status.
Every group of people that comes together through a common interest has an underlying philosophy, whether or not anyone in the group has put it into words (or even correctly identified it, if they’ve tried to put it into words). As long as the group isn’t organized around a shared belief in the supernatural, so that the group members all jump to the same conclusions about supernatural forces, then secular debating is the only way forward. Even a group made up of people of different religions is a good place to talk about secular values, because the stuff in this world is the only thing everyone has in common.
Then what ideas is their philosophy built upon? Every philosophy contains an interpretation of the first two laws of thermodynamics and the theory of evolution. First Law of Thermodynamics: The Earth is a finite size (technically, the matter and energy content of the universe is finite). Second Law of Thermodynamics: Change creates variation, which includes both destruction and diversity (technically, entropy tends to increase). Theory of Evolution: Complicated stuff is made up of simpler stuff (technically, cumulative adaptation to environmental pressures). You don’t need to tell people the science directly, because they already know the basics ideas. Instead you can talk about different ways you’ve each seen these things play out. That way you aren’t telling them their ideas are wrong, but agreeing with them on basic principles. Then you can expand the other person’s horizons and expand your own horizons in the process. Every minority has thought about ideas and noticed patterns of human behavior that people in the majority haven’t.
So instead of approaching this overall project from the proposed direction and facing the challenges of organizing such a thing, if individual people develop the necessary skills and mental discipline, they can identify other people’s projects that are already moving in this direction and help expedite their convergence on this point, simply helping the other people reach their own goals.
Simple as that. 
