The earliest surviving Christian documents are the letters of paul. The authorship of some letters (or "epistles") traditionally attributed to him is disputed, however. The so-called "undisputed" letters, in the order in which they appear in the New Testament, are:
- 1 & 2 Corinthians
- 1 Thessalonians
The letters of "disputed" Pauline authorship are:
- 2 Thessalonians
The "Pastoral" epistles are widely regarded as "pseudonymous" by NT scholars:
- 1 & 2 Timothy
The book of Hebrews is almost universally agreed not to be a product of Paul's writing.
For a scholarly orientation to this topic, see Stanley E. Porter, “Pauline Authorship and the Pastoral Epistles: Implications for Canon”, [pdf] Bulletin for Biblical Research 5 (1995): 105-123.