Scripture & Supper as Boundary Markers

George Aichele says:

The question of canon arises in the form of disputes over which are (or who possesses) the genuine scriptures…. Finally, however, they are also disputes over the identity of the reading community. Canon arises from the need to distinguish Jews from Christians, Ebionites from Marcionites, and so forth. (Sign, Text, Scripture: Semiotics and the Bible, Sheffield Academic Press, 1997, p128)

This is clearly not all that is going on, but perhaps there's some truth in saying that confession of the canonical Scriptures, like being baptized and recieving the Lord's Supper, serves as a boundary marker of the Christian community. Indeed, believing the Word of God and duly recieving the sacraments are marks of the Church. Israel at Sinai might be taken as a prototypical picture of the church marked out by being gathered around the Word of God.