

If possible (last I heard, it was out of print but they were considering 
reprinting) read Barbara Hambly's _Search the Seven Hills_.  It is 
historical fiction, set in Rome at the time of the early Church.  She 
captures the weirdness of the early Christians and yet gives glimpses of 
the holiness too.  Some of their odd views make a lot more sense in the 
context of the society they lived in.  I found it a remarkably positive 
view of Christianity considering that the author is not a Christian 
herself.  Another plus is that each chapter begins with an 
original-source quote so that it makes a good starting point for serious 
research.