A Sunday School class, some time ago, dealt with the resurrection of Christ. Why is that event so important? The Bible answers that, in these passages, and others:
Acts 2:32 This Jesus God raised up, and of that we all are witnesses. 33 Being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit, he has poured out this that you yourselves are seeing and hearing. 34 For David did not ascend into the heavens, but he himself says,
“‘The Lord said to my Lord,
Sit at my right hand,
35 until I make your enemies your footstool.’
36 Let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified.” (The resurrection was important enough that Peter mentioned it in his sermon on the day of Pentecost. It was also important enough that Peter had courage to give the sermon.)
Acts 17:18 Some of the Epicurean and Stoic philosophers also conversed with him. And some said, “What does this babbler wish to say?” Others said, “He seems to be a preacher of foreign divinities”—because he was preaching Jesus and the resurrection. (Apparently the philosophers on Mars Hill misunderstood Paul. He mentioned the resurrection so much that they thought it was another god.)
1 Corinthians 15:14 And if Christ has not been raised, then our preaching is in vain and your faith is in vain. 15 We are even found to be misrepresenting God, because we testified about God that he raised Christ, whom he did not raise if it is true that the dead are not raised. 16 For if the dead are not raised, not even Christ has been raised. 17 And if Christ has not been raised, your faith is futile and you are still in your sins. 18 Then those also who have fallen asleep in Christ have perished. 19 If in this life only we have hoped in Christ, we are of all people most to be pitied.
20 But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep.
Ephesians 1:19 and what is the immeasurable greatness of his power toward us who believe, according to the working of his great might 20 that he worked in Christ when he raised him from the dead and seated him at his right hand in the heavenly places, 21 far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in the one to come.
1 Peter 1:3 Blessed be the God and Father of our Lord Jesus Christ! According to his great mercy, he has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, 4 to an inheritance that is imperishable, undefiled, and unfading, kept in heaven for you, 5 who by God's power are being guarded through faith for a salvation ready to be revealed in the last time. (The resurrection, said Peter, is our only real hope.)
All scripture above is from the English Standard Version. I added the emphases.
Thanks for reading!