For some, it is difficult to give up religion even though they understand it’s not real. It is especially difficult for ministers and pastors who not only define their social networks by their (now non-existent) religious beliefs, but are expected by those communities to lead them in those (now non-existent) religious beliefs.
In 2011, Daniel Dennett and Richard Dakwins helped set up The Clergy Project, a community specifically aimed at religious leaders who had become deeply closeted atheists.
The first member of the Clergy Project community to out himself was Jerry DeWitt, who went on to establish Recovering From Religion, designed to help regular people deal with the “sheer terror” referred to above.
Atheists do not naturally form communities. They have literally nothing in common except a lack of belief in gods. However, these organisations (among others) mean that no one has to feel alone.