I have argued in numerous places–articles, blog posts, books–that Scripture played a central role in the life of early Christians. They not only read and preached from these books, but they copied and distributed them in great numbers.
An additional (and rather curious) example of the role of Scripture in early Christianity was the phenomenon of the miniature codex. From the time of the third century, and especially in the fourth and fifth centuries, Christians began to create these little “pocket Bibles” that contained portions of Scripture and sometimes even held multiple scriptural books (e.g., see my analysis of P.Ant. 12).
The early Christians probably used the miniature codex format for a number of reasons including private reading, portability for long journeys, and sometimes even in a “magical” sense (thinking it provided protection for the one who possessed it).
But, it seems they also used these books as a visible sign of their Christian identity. Christians would carry these books on their bodies, often hung around their necks, as a sign that they were devoted to Scripture and thereby devoted to Christ.
Aside from the miniature codex in particular, we know Christians often treated scriptural books in just such a fashion. For instance, a biblical codex was placed on a throne at the Council of Ephesus (c.431) as a powerful visual representation of the presence of Christ.
Similarly, Epiphanius describes the power of just seeing scriptural books, “The mere sight of these books renders us less inclined to sin, and incites us to believe more firmly in righteousness.”
The monk Philoxenus of Mabbug (fifth century) shows a similar devotion to the Gospels as a physical object: “Take the Gospel in your hands. Place it on your eyes and your heart…place the Gospel on the cushion and prostrate yourself before it up to ten times… [and] you will conceive in your heart the internal adoration and the effect of divine grace.”
In light of this context, we have a few possible examples of the “devotional” use of the miniature codex. For instance, Maximus, disciple of the fourth-century Martin of Tours, hung a “book of the Gospels” around his neck during his travels, along with the instruments of the sacrament (a small paten and chalice).  Apparently the tiny Gospel book was a way for Maximus to put the tools of his divine trade on full visual display; i.e., to identify himself as minister.
In 304, a Christian deacon named Euplus was martyred in Catania under the Governor Calvisianus with the “book of the Gospels” hung around his neck. Indeed, he presented this very gospel book to the authorities as proof that he was a Christian.
Similarly, Chrysostom, noting how the Israelites were commanded to carry the Scriptures with them in Deut 6:6-9, commends those who do the same, “Many of our women now wear Gospels hung from their necks. And in order that by another thing again they may be reminded …and remember the commandment.”
These examples provide an interesting glimpse into the mindset of early Christians. So devoted to Scripture were they, that they often wore the books on their body as a signal to all watching that they were committed to following these books and the message they contained.
 Benedicta Ward, trans., The Sayings of the Desert Fathers: The Alphabetical Collection (London: Liturgical Press, 1984), 58 (Epiphanius 8).
 Rapp, “Holy Texts,” 198.”
 Raymond Van Dam, trans., Gregory of Tours: Glory of the Confessors (Liverpool: Liverpool University Press, 1988), 37.
 H. Musurillo, Acts of the Christian Martyrs (Oxford: Clarendon, 1972), 319 (Latin recension).
 Hom. Matt. 72.2. Scholars are divided over what Chrysostom is doing in this passage, but we cannot explore that issue further here.