John Dominic Crossan has provided a detailed classification of our sources for the historical Jesus according to the chronological stratification of the traditions. For a brief discussion of each source, including the reasons for its proposed dating, see John Dominic Crossan, The Historical Jesus (HarperCollins, 1991) Appendix 1, pp. 427-50. All dates shown are C.E. (Common Era).
First Stratum [30 to 60 C.E.]
1. First Letter of Paul to the Thessalonians (late 40s)
2. Letter of Paul to the Galatians (winter of 52/53)
3. First Letter of Paul to the Corinthians (winter of 53/54.)
4. Letter of Paul to the Romans (winter of 55/56)
5. Gospel of Thomas I (earliest layer of Thomas, composed in 50s)
6. Egerton Gospel (50s)
7. P. Vienna G. 2325 (50s)
8. P. Oxyrhynchus 1224 (50s)
9. Gospel of the Hebrews (Egypt, 50s)
10. Sayings Gospel Q (50s)
11. Miracles Collection (50s)
12. Apocalyptic Scenario (50s)
13. Cross Gospel (50s)
Second Stratum [60 to 80 C.E.]
14. Gospel of the Egyptians (60s)
15. Secret Gospel of Mark (early 70s)
16. Gospel of Mark (late 70s)
17. P. Oxyrhynchus 840 (?80s)
18. Gospel of Thomas II (later layers, 70s)
19. Dialogue Collection (70s)
20. Signs Gospel, or Book of Signs (70s)
21. Letter to the Colossians (70s)
Third Stratum [80 to 120 C.E.]
22. Gospel of Matthew (90)
23. Gospel of Luke (90s)
24. Revelation/Apocalypse of John (late 90s)
25. First Letter of Clement (late 90s)
26. Epistle of Barnabas (end first century)
27. Didache (other than 1:3b2:1, 16:35) (end first century)
28. Shepherd of Hermas (100)
29. Letter of James (100)
30. Gospel of John I (early second century)
31. Letter of Ignatius, To the Ephesians (110)
32. Letter of Ignatius, To the Magnesians (110)
33. Letter of Ignatius, To the Trallians (110)
34. Letter of Ignatius, To the Romans (110)
35. Letter of Ignatius, To the Philadelphians (110)
36. Letter of Ignatius, To the Smyrneans (110)
37. Letter of Ignatius, To Polycarp (110)
38. First Letter of Peter (112)
39. Letter of Polycarp, To the Philippians, 1314 (115)
40. First Letter of John (115)
Fourth Stratum [120 to 150 C.E.]
41. Gospel of John II (after 120)
42. Acts of the Apostles (after 120)
43. Apocryphon of James (before 150)
44. First Letter to Timothy (after 120)
45. Second Letter to Timothy (after 120)
46. Letter to Titus (after 120)
47. Second Letter of Peter (between 125 and 150)
48. Letter of Polycarp to the Philippians, 112 (140)
49. Second Letter of Clement (150)
50. Gospel of the Nazoreans (middle second century)
51. Gospel of the Ebionites (middle second century)
52. Didache, 1:3b2:1 (middle second century)
53. Gospel of Peter (middle second century)
In addition to the above, modern analytical bible scholars have intensively studied the text of those epistles that are generally attributed to Paul. By closely examining vocabulary, grammar and thought themes they are in agreement that the following epistles are genuinely from Paul. They are 1 Thessalonians, 1 and 2 Corinthians, Galatians, Philippians, Philemon and Romans. Two more letters, Colossians and 2 Thessalonians are in dispute. Hebrews does not reflect Paul’s style and content whatsoever. Ephesians does not reflect the style of Paul but is very much Pauline in content and is thought to have been written by a close follower of Paul’s. The Pastoral letters (Titus, 1 Timothy and 2 Timothy) are attributed to Paul, but someone writing in Paul’s name wrote them around AD120, some 60 years after Paul’s death. Each letter uses vocabulary Paul is not known to have used; each has a different concept than Paul had of key matters such as faith; and each refers to Paul’s close friends Timothy and Titus in formal rather than friendly terms. They assume that Christian churches are governed by the kind of carefully organized authority structures that developed decades after Paul’s time. They are similar in style and in content and in the issues they raise. Scholars generally believe them to have been written by the same person. In addition two of Paul’s epistles are thought to be composed of what were originally several smaller letters. In particular Philippians is composed of three and 2 Corinthians is composed of six. Chapter 16 of Romans seems to be a later addition but genuinely by Paul.