It's probably surprising to others, and definitely surprising to me, that as churchless as I am, one of my favorite meditation books is Open Mind, Open Heart by Thomas Keating, a Catholic priest, monk, and abbot.
(There's a new edition of the book, but I'm familiar with the old one, and the new one is more difficult to read typographically, from Amazon reviews I've read.)
I've written some blog posts about the book, which I bought in 2005.
The basic technique described in Open Mind, Open Heart is what Keating calls centering prayer. Except it isn't at all like the usual Christian notion of prayer. You aren't asking for something from God, but opening yourself up to God via outer and inner silence.
Of course, right there an atheist like me has a problem with the book, since I don't believe in God. But Keating says:
Every response to God, whatever it is, must begin with the full acceptance of reality as it actually is at the moment.
So I mentally substitute "reality" for "God" in the book.
This leaves centering prayer as closely akin to other forms of meditation in which one's attention is focused on the breath, a mantra, or some other object of attention while thoughts and other perceptions are allowed to come and go.
The next problem I have with the book is that Keating believes in pure awareness. Or at least, almost pure awareness. But so does Sam Harris and other Buddhist types, so I just look upon pure awareness as a possibility that doesn't make much sense to me, yet isn't all that crazy.
Especially since I've argued for it in the past, including in the first book I wrote, God's Whisper, Creation's Thunder.
What I find refreshing about Open Mind, Open Heart is how Keating presents the via negativa approach to God in a modern fashion. That Wikipedia article includes a quote from Plotinus, an ancient Neoplatonist philosopher who I wrote a book about, that echoes what centering prayer is all about.
Our thought cannot grasp the One as long as any other image remains active in the soul [...] To this end, you must set free your soul from all outward things and turn wholly within yourself, with no more leaning to what lies outside, and lay your mind bare of ideal forms, as before of the objects of sense, and forget even yourself, and so come within sight of that One.
Keating describes how he views consciousness and God.
Our consciousness, as we have said, is like a great river on the surface of which our superficial thoughts and experiences are moving by like boats, debris, water skiers or other things. The river itself is the participation God has given us in His own being.
It is that part of us on which all the other faculties rest, but we are ordinarily unaware of it because we are absorbed with what is passing by on the surface of the river.
In centering prayer we begin to shift our attention from the boats and objects on the surface to the river itself, to that which sustains all our faculties and is their source. The river in this analogy has no qualities or characteristics. It is spiritual and limitless because it is a participation in God's being.
Suppose you get interested in some boat and find yourself looking in the hold to see what is on board. You are slipping away from your original intention. You must keep turning your attention from what is on the surface of the river to the river itself, from the particular to the general, from forms to the formless, from images to the imageless.
...A thought in the context of this method is any perception that appears on the inner screen of consciousness.
This could be an emotion, an image, a memory, a plan, a noise from outside, a feeling of peace, or even a spiritual communication. In other words, anything whatsoever that registers in the inner screen of consciousness is a "thought". The method consists of letting go of every thought during the time of prayer, even the most devout thoughts.
Thus Keating views human consciousness as a gateway to God when consciousness is reduced to inner silence. OK, interesting theory, one which I used to embrace -- which probably explains why I'm attracted to Open Mind, Open Heart, though I doubt that some basic tenets of the book are true.
Keating speaks positively about Eastern forms of spirituality. Not surprising, since he's basically espousing an Atman (consciousness/soul) -- Brahman (God) form of Christianity.
Probably false, but at least Keating presents a specific method of reaching out to God that makes more sense than the whole "Just have faith in Jesus" thing.