When, in addition to the Hebrew Bible, the church recognized twenty-seven writings as authoritative for matters of faith and practice, it took an unusual step. Most religions do not include letters in their canons of Scripture. Letters ostensibly belong to the category of occasional literature; that is, they are prompted by and written for particular occasions. In addition to the twenty-one New Testament books in epistolary form, Acts and Revelation have letters embedded in their narratives. The New Testament letters fall at various points on a continuum between the formal (Romans, Hebrews) and the informal (Philemon, 2-3 John). The most consequential of the early Christian letter writers is the Apostle Paul. Thirteen letters are attributed to Paul. Hebrews was included among his letters prior to the Reformation, Peter mentions his letters, and the Letter of James is sometimes interpreted as a response to Pauline teachings.