The book suggests that the defining problem driving out most people who leave is … just how American life works in the 21st century. Contemporary America simply isn’t set up to promote mutuality, care, or common life. Rather, it is designed to maximize individual accomplishment as defined by professional and financial success. Such a system leaves precious little time or energy for forms of community that don’t contribute to one’s own professional life or, as one ages, the professional prospects of one’s children. Workism reigns in America, and because of it, community in America, religious community included, is a math problem that doesn’t add up.
Christianity is currently dominant because it flirts with worldly power, It's not really Christianity at all. I call it Unironic Satanism: the worship of capital, military, imperialism, police, politicians, and reactionary institutions. So, in a sense Original Christianity is essentially dead. Nietzsche wasn't wrong when he said, "God is dead and we have killed him... Who gave us the sponge with which to wipe the horizon from the sky?" This is the state of our current world. We have committed the ultimate blasphemy collectively. We have defiled the sacred and buried it away, all because life is painful and unjust. Who could believe in a God when there is so much vast suffering and unimaginable injustice? It's not even a question for many.
Also, the current form of reactionary Christianity in the West is a fantasy death cult, whereby reactionaries can retreat into a fantasy about apocalypse and rapture that will finally wipe away all of the sin and pain from the world. Sorry pal, that aint happening. We were given intelligence and resources to save ourselves. Hear no evil, see no evil, speak no evil is not a survival strategy, it's the most evil form of ignorance.