The ICR devotional article in Days of Praise, “Preaching the Ressurection” (see https://www.icr.org/articles/type/6), highlights the truth of how Christ’s apostles preached a message of the bodily ressurection of Jesus and were convinced enough to sacrifice their own lives for that scriptural truth. That alone is solid enough evidence that could stand up in a court of law, underscored by the eye witness testimonies of not only the apostles, but of the multitude indicated in 1 Cor 15:6 “After that He appeared to more than five hundred brethren at one time, most of whom remain until now…” The Gospel accounts provide even more concrete testimonies. That nullifies any notion that the Lord’s resurrection was only spiritual.
Christians must stand their ground in holding to the core Gospel truth about Jesus Christ against any false doctrine, which is the main message in Galations as well as 1 Cor 15. It is a crucial test of one’s own salvation: “That if you confess with your mouth Jesus is Lord, and believe in your heart that God raised Him from the dead, you shall be saved; for with the heart man believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation.” Roms 10:9, 10 (NASB)