This is a subsidiary post of Truth in the New Testament.
It is also a subsidiary post of The Apostles and the Truth.
It is also a subsidiary post of Apostles.
It is also a subsidiary post of The Nature, Purpose, and Value of Witness and Testimony in Ancient Israel
The legitimacy of Christianity is based upon the truthfulness of the apostles, and, most specifically, their truthfulness about the resurrection of Jesus Christ from the dead. If the apostles are deemed to be telling anything other than the truth then the basis for Christian faith collapses.
1 Corinthians 15:1-20 (especially 1 Corinthians 15:14-15)