This page shall be occasionally updated as more material is posted to Into the Clarities; more than that, it shall, before long, be completely rewritten.
Before looking at what the modern trends of secularization mean, one must understand something of what Christianization was, as secularization begins to operate within Christianized cultures, and when it operates, seeks to translate, mute and/or remove some of its elements — using categories drawn from within Christendom itself. (“Secularization” first appears in the wake of the 16th century Reformations, and describes the transference of properties from the Catholic Church to the secular rulers.)
As far as surveys go, Peter Brown is a good resource for thinking about the significance of Christianization, as is Ramsay MacMullen, coming as he is from a very different angle. Averil Cameron has written some fantastic material; Philip Rousseau and Judith Herrin, likewise. One should not overlook Robert A. Markus (who has written on the roots of secularity in the writings of Augustine of Hippo, on Augustine’s innovative understanding of signs, on the end of Late Antique Christianity, and on figures such as Gregory the Great) nor Robert M. Grant. W. H. C. Frend and the Chadwick brothers have written essential volumes. Timothy D. Barnes is also worth reading; I hope to get to Frank R. Trombley soon.
More focused studies might dwell upon figures such as Lactantius, Constantine, Eusebius, Ambrose, Prudentius, and Augustine (I have written on his indebtedness to Plotinian themes in his Confessions). One ought to spend some time with the Cappadocians (Gregory of Nyssa, Gregory of Nazainzus, and Basil of Caesarea) at some point.
The emperors deserve their own treatment, as does the Late Antique legal tradition — civil and canonical.
Philosophical figures such as Plotinus, Iamblichus, Proclus, Simplicius, Boethius and Philoponus cannot be ignored (nor can the work of Richard Sorabji, John Dillon or Eric Perl for this period, among many others). The figure of Pseudo-Dionysius (or simply “Denys”), in many ways, sits at the beginning of the crescendo of this Late Antique tradition within the realm of theological reflection itself, and it is important to know this theological tradition to see the ways it was inherited in the medieval and early modern period (the impact is surprising to the point of being shocking); expect to see more about Denys in the future (I have compiled a columned comparison of three translations of his Epistle 9, and another columned comparison of translations of Book 1 of his work On the Divine Names).
Topics bearing upon Christianization range widely; expect to see more in the coming year, and beyond.