The Gospels were written forty to sixty years after the events by anonymous authors who were not eyewitnesses. Why treat them as evidence at all?

Forty to sixty years is well within living memory, which is why the Gospels are paired here with Paul’s much earlier witness list rather than standing alone. The anonymity point is overstated: the Gospels circulated under their traditional names from the earliest external attestation we have, and Luke says explicitly that he drew on eyewitness sources. Even a reader who dates them late and rejects the traditional authorship still has to explain why four documents from different communities converge on the same core: crucifixion, burial, empty tomb, and appearances to named people who at first doubted.