How did Jesus become a God?
Larry Hurtado has a well deserved reputation for his excellent work on the origins on Christian worship. As such, he has also made a welcome contribution to the debates over Christology in the earliest church. Happily, thanks to St John’s Nottingham, he can speak for himself.
Q and the Historical Jesus

A good example of current work on the Historical Jesus can be found at the Thoughts on Antiquity site, and in particular the short, ongoing series on Q by Chris Zeichmann.
I mention this as it is interesting to see the thought processes and methods behind this strand of New Testament work, regardless of your confidence in attempts to reconstruct a Christ who does not reflect current sensibilities!
Mysticism

I mentioned yesterday some spiritual themes from John’s gospel. A superb survey of this and the development of Mysticism generally is Thomas Merton’s “An Introduction to Christian Mysticism”. Be warned, though, that it is not a book but rather lecture notes for course run for novice monks. It means that it is a bit condensed to read, but the material is very good indeed.
You can read an excerpt here. The book is published by Cistercian Publications.