1 Corinthians 15 early creed: dating, content, and the list of resurrection witnesses including Peter, James, Paul, and the 500

The creedal formula in 1 Corinthians 15:3-8 — Christ died, was buried, rose on the third day per the Scriptures, appeared to Cephas, then the Twelve, then 500 (most still alive), then to James, then to all the Apostles, then to Paul — is likely derived from within 5 years of the resurrection, possibly as early as 2-3 months post-resurrection. These three (Peter, James, Paul) stayed as traveling witnesses guaranteeing the truth of the resurrection, and they died for that proclamation.