I have a slightly different problem. I've been a nonbeliever for about 4 years, but I was already struggling with my faith for far longer, so its obvious to me the christian religion is man made, as are all other religions.
However, what bothers me is that I really miss the church. It helps that the churches I went to were not filled with bible belt rednecks (I live in seattle), but rather fellow asian americans who were humble, kind, caring, overachieving doctors, lawyers, and engineers, and who happened to be able to compartmentalize their faith from their otherwise intelligent and rational selves. guys like newest NBA superstar Jeremy Lin. in sunday service, bible studies, retreats, and mission trips, we would support, encourage and uplift one another. this is what I loved about christianity. it was a wonderful time, and it did a lot of good in my life. of course, its completely made up. but i don't think i could ever go back, even though at times I badly want to.
I'm lucky that I have lots of atheist friends and hobbies, but at the end of the day, its not quite the same as the church. personally, i suspect most people in church are more or less agnostic, or consider the bible to be mostly just stories, and quietly push aside all their nagging doubts, so that they can have access to this wonderful and motivational social club.
i would love to attend a "church" of fellow ex christians, who i would be able to relate to and understand, and who still have that same positive, loving, and optimistic attitude that their faith once instilled in them. too many atheist meetups i've been too the apostates have become really embittered about it all (i was too for a long time), and that was too much negative energy for me.