The New Testament in Its World: An Introduction to the History, Literature, and Theology of the First Christians by NT Wright. It's like several seminary level classes rolled into one book, and distills decades of brilliant scholarship by NT Wright with respect to the New Testament. It goes over things like the historical Jesus, the Jewish, Greek, and Roman contexts of the New Testament, the history of the Jews in the Second Temple Period leading up to the time of Jesus, the cultural significance of the Resurrection, and so many other things. It's not too technical, either. I highly recommend every Christian read it who wants to go beyond basic level Bible study.