Refutation: early manuscripts from well before the 13th century already contain the longer ending of Mark; the addition was likely scribal, not conciliar — probably constructed from Luke, Acts, and Matthew to give public readings a more complete feel

We have manuscripts containing the longer ending dating well before the 1300s, so the 13th-century Jewish council claim is false. The more plausible explanation is that scribes constructing readings of Mark pulled content from Luke, Acts, and Matthew to give the narrative a more complete arc for public reading, then that constructed ending was copied into subsequent manuscripts without clarity about whether it was commentary or original text. Mike also notes this does not threaten the authority of Scripture.