PZ Myers and most of his commenters appear to have completely missed the point of Religion for Atheists.
They also completely exaggerate the importance of belief in religions. Alain de Botton is right that whether or not God exists is a boring question. It's been pretty well settled that God does not exist. Some theologians have got round this problem by saying that this is because God is existence, or the Ground of All Being, but then that leaves the question of what that might mean.
I'm glad that the New Atheism has raised the stakes in the theological game, and brought non-realist and apophatic theology to the fore again, but I dislike the way some New Atheists dismiss all religion as harmful rubbish.
Most religions are centred around practice rather than belief. In Hinduism, Paganism, Buddhism, Taoism, Unitarianism, Quakerism and Judaism, belief is not central to whether you count as a member of the religion or not. What counts is either values or practices. The question for Jews is not "Do you believe?" but "Are you observant?" For Pagans, what counts is your attitude to nature, the earth, and/or the land. There are many different schools of thought in Hinduism, Taoism, Paganism, Buddhism, Taoism, Unitarianism, and Quakerism, ranging from theists to non-theists. For Buddhists, deities may well exist, but they are irrelevant. Many Pagans and Unitarians would agree with the Buddhists on this. Many Unitarians are atheists and humanists.
So if it is not about providing an explanation of how the world works or how it came into being, what is religion for? It is about providing a system of shared meaning, and a set of spiritual practices (meditation and ritual), and a community to share ideas, joys and sorrows.
In liberal religions, you don't need to sign up to a set of axioms or propositions which may offend against your reason in order to be part of the community and make use of a collection of stories, mythology, symbols and practices.
Religious community also inspires people to band together to create social justice (although non-religious groups do this too). By consistently encouraging members to treat others with compassion, religious community can be a powerful tool for creating change. Think of Martin Luther King, Mahatma Gandhi, and others who were inspired to change the world.