There are, naturally, a number of excellent points that I could highlight here; as I read I find myself underlining just about every line and trying to cram my comments into the margin. Here I think I'll just comment on one particular phrase that I've come across twice in the first ten pages; there will be plenty of time later for additional comments.
One of the problems facing scholars of Christian origins concerns how to understand the tension between (i) the nearly assuredly low literacy rates across the early Roman Empire (including among Christians), rates which may have rarely if ever exceeded twenty per cent in some urban areas, and (ii) the equally secure fact that the early Christians produced, transmitted, and poured over a surprising number of texts. These latter weren't simply early Christian texts (gospels, letters, homilies, etc.) but just as importantly Hebrew biblical texts; from the very beginning Christians valued Moses, the prophets, and (to a lesser extent) the later writings.1 The impression that texts played a vital role in early Christianity isn't simply a by-product of the dominance of written texts among the extant evidence; from the very earliest images we get of the church the presence and public reading of texts loom large (e.g., 1 Tim. 4.13; Justin, 1 Apol. 67). Gamble rightly recognizes both poles of this tension. Most early Christians—probably more than four out of every five—were functionally illiterate, and written texts played a vital role in the construction and expression of early Christian identities.
In my own research I have used a distinction between literacy (the ability to read written texts) and textuality (access to written traditions) to navigate this tension. Gamble has a wonderful phrase that I find at least as helpful, if not more, for this purpose. On two occasions he speaks of participation in literacy.
If most Christians were illiterate, it did not prevent them from participating in literacy or from becoming familiar with Christian texts. . . . Thus, although the limited extent of individual literacy certainly had a bearing on the composition, transcription, private use, and authoritative interpretation of Christian texts, it had little adverse effect on the ability of Christians generally to gain a close acquaintance with Christian literature. The illiterate Christian found in the public reading of Christian texts at least as large and probably a more consistent opportunity than his pagan counterpart to participate in literacy and become familiar with texts. (8–9)
This phrase—participation in literacy—needs to gain wider currency among scholars of Christian origins. It will help us to recognize the centrality of written texts in early Christian experiences (pace, e.g., Richard Horsley, who can be read to imply that written materials were alien things that only existed in Jerusalem, Athens, Rome, and other exotic places) even as we respect the rather different avenues of access available to the typical Christian, the believer who was completely unable to "take up and read" (pace the picture of early Christianity [and Judaism] Horsley is trying to displace).
1 Notice, for example, that when Luke enjoins gentile believers to abstain from the meat of animals offered to idols or from strangled animals, from blood, and from fornication (Acts 15.20), he bases these injunctions on the fact that "Moses, who is read in the synagogues on every Sabbath, has had in every city from generations past those who proclaim him" [Μωϋσῆς γὰρ ἐκ γενεῶν ἀρχαίων κατὰ πόλιν τοὺς κηρύσσοντας αὐτὸν ἔχει ἐν ταῖς συναγωγαῖς κατὰ πᾶν σάββατον ἀναγινωσκόμενος (15.21)]. Whatever Luke may mean here, the obvious point is that the church as he presents it values Moses and expects new members to make ethical decisions in light of others' high valuation of Moses and his texts (ἀναγινωσκόμενος).