Mr. Mitchell is my favorite author right now. "The Bone Clocks" features two of Mr. Mitchell's themes - The Soul and Time.
While none of Mr. Mitchell's books focus on religion he clearly has an interest in our soul. While I cannot say this, or any of his books, are spiritual several do involve the transference of Souls or the equivalent.
I mentioned time; I do not mean time travel or any other tricks with time. Mr. Mitchell uses Time (and the Soul) to create a sense of expansiveness in his works. The Bone Clocks goes from 1984 to 2043 and a lot changes.
One other technique Mr. Mitchell is very adept at (maybe the best at?) is leveraging multiple narrators ("Cloud Atlas") with different and distinct 'voices'. What I like here was almost all the narrators start out as very unlikeable. But grow on you by the time there story ends. And then the next part starts with a new narrator that that is not likeable. Very disconcerting.