Acts chapter 26 - questions for discussion

Introduction
Paul presents the gospel to King Agrippa and Bernice. Festus is  their host.

Once again Paul takes them through the gospel using the testimony of his conversion as the main point.

You will notice that it is actually the gospel that is on trial and not Paul. Some of Paul's most popular quotes are also used here.

"Therefore King Agrippa I was not disobedient to the heavenly vision"
Acts 26:19.

When Paul gets to the truth about the resurrection, again Festus interrupts him, accusing Paul of going mad due to too much learning.
No doubt Paul was well learned and educated and considered an intellectual voice to be reckoned with in his day.

The anointing and strength of Paul's argument nearly converted King Agrippa (Acts 26:28).

Our gospel does make logical sense,but except a man receives it by faith it will not result in salvation.

Question
1. Why is the resurrection of christ from the dead so vital to the gospel?