My suggestion: The Origin of the Four Gospels, by Constantine Tischendorf,
In the mid-1800s some European scholars began to view the Bible as something other than 'the literal word of God' or similar. (It claims to be the word of God, written by men from "dictation"- under the direction of God's spirit.)
This is Tischendorf's reply to such- by name- and is quite interesting on the subject.
It also shows the tremendous amount of work and thought involved in Bible scholarship. Almost everything T. refers to outside the Bible is available on CCEL (Ignatius, Eusebius et al.) Made me appreciate more those who came before us.
BTW I just finished 'editing' the .pdf download of Origin, to move the endnotes into a handier format. The notes themselves are printed twice: once in the body at the endnote number, and again in the endnotes. It took time, but it made the .pdf (my preferred format) much easier to study.