Many believers use the Psalms as a prayer book. It is also primarily God’s hymn book. From the early church the Psalter has been both the prayer and hymn book of the church. The author indicates this for the apostolic church and the church of the early church fathers. He continues with the Middle Ages and the Reformed tradition.
The canonicity of the Gospels was an issue that arose in the period from the second to third century. In this time the church was determining the authority of these Gospels. In this article Richard Bauckham looks briefly at the way in which apostolic eyewitness functioned as a criterion of authenticity.