There are 3 books in the series - I've read 2 of them and not the third.
I enjoyed the first book more than the second - the first one was how he got to speaking to God - now do I believe that it was an outside God as most christians perceive God - no - I think it was his spiritual awareness that awoke in him and since he didn't know how to define it - called it God. It was an interesting read and he posed interesting questions - I didn't believe everything but there are some gems. The second book I found it waffled on a bit, using a ton of words to say nothing much. The third book then goes onto sexuallity - I haven't read it so don't have an opinion of it.
I think if you're interested in Spirituality you should have a read. I can also suggest A New Earth and the Power of Now both by Eckart Tolle. A couple of other good spiritual writers are Emmet Fox, Goldswain and then there is a book called "A book on Miricles" (I'll double check that one)