I just finished Why Christianity Must Change or Die by Bp. Spong. I found the book to be largely unconvincing, though that might have come partially from an unfamiliarity with the concept of God that he was trying to argue for. I think if I had read more of authors such as Paul Tillich, I would have better understood exactly where Bp. Spong was going in this book. Even then, though, there seemed to be a streak of pessimism in the book that I found off-putting. For example, Bp. Spong says that Christians use terms like "divine" and "almighty" as an attempt to flatter God and get something out of it (p. 139). Surely most Christians use such terms because they believe it proper to reverence God. I also just started another book by Bp. Spong, Resuing the Bible from Fundamentalism, though it's too early to form any opinions about this one. As to why 2 books by this particular author: I had for years heard bad things about him, and had perhaps even myself said a bad thing or two about him, so I figured I owed him a fair hearing.
I also recently started The Existence of God by John Hick. This is a book I first read 8 years ago, when I was in a similar spiritual place. I recalled it helping me then, so I figured I'd give it another shot. Basically the book gives the arguments for the existence of God, and then allows different authors to offer commentary and opposing views. Hick believes that you cannot argue someone into believing in God through these proofs (which I would agree with, eventually there must be a place for faith), but still considers it an important topic.