He has written this book to show that science can not only justify and authenticate religious belief, it can also help improve it.
The spiritual practises he examines include prayer, mediation, ritual, communing with nature, pilgrimage, psychedelics, gratitude - and sport!
He writes: There are many spiritual practices, and most of them have now been studied scientifically. There is powerful evidence for their benefits in modern secular societies. There has been a dramatic decline in traditional religious observance, but most people continue to believe in the reality of the spiritual realm, even if they are not sure what it is or what name to give it.
Spiritual practices often lead to a feeling of connection with a consciousness greater than oneself. All religions involve spiritual practices, and the practices of different religions are often very similar. Even some atheists follow practices like mindfulness meditation, and some, like Alain de Botton, in his Religion For Atheists, call for a reinvention of spiritual practices for atheists.
In this book I discuss a wide range of practices in which I myself have some experience, and which readers can try for themselves. In each chapter, I make several suggestions about how to follow the practice I am discussing.
I am a Christian myself, an Anglican, and therefore have more experience of Christian spiritual practices than those of other traditions. But I was also an atheist for more than a decade, a practitioner of Indian traditions of yoga and meditation, and a follower of Sufi practices. I have attended Tibetan Buddhist retreats, and worked with several shamans. Many of my friends describe themselves as spiritual but not religious.
Spiritual practices can give immediate experiences of being linked to, or in communion with, a greater consciousness than our own. For materialists, who believe that matter is the only reality, these experiences are all inside the brain. They may involve triggering off responses from pleasure centres, or the release of neurotransmitters like anandamide, an internally-produced cannabis-like molecule, or other physical and chemical changes. But all attempts to explain ineffable experiences exclusively in term of the activity of nerves and molecules depend on materialist assumptions, which are beliefs. Should belief take precedence over experience?
Are our minds connected to a collective human consciousness? Do they go further than humanity, and connect us with the consciousness of the earth, Gaia? Or do they go further still, to the solar system, the galaxy, or the entire cosmos? Is the mind or soul of the universe the ultimate reality, or does it itself depend on an ultimate conscious reality that transcends the universe? Is God not only in nature, but nature also in God?