In the book Jesus, Who Is He?, the famous author of the Left Behind
series Tim LaHaye shares a deep reflection on the impact that not only
Jesus’ life and death, but especially His resurrection, have had on all
those who believe.

To rise from the dead is what gives authenticity to everything else.

Christ’s execution may well be considered a tragic, illegal miscarriage of justice, but when we include the resurrection, the message of the cross becomes glorious victory. Jesus’ resurrection is what gives power to the cross and proves Christianity’s reliability. As Napoleon put it, “you must die on a cross and rise on the third day” to found a religion.
Jesus resurrected physically, not just in spirit. A specter does not walk, talk and eat like Jesus did with the two disciples on the road to Emmaus, thus inquiring them: “Why are you troubled? (…) See my hands and feet, that it is I myself; handle, and see: for a spirit hath not flesh  and bones, as you see me to have.” (DRA)
You could say that the true Christian believes in Christ’s death for our sins, in the entombing of his body in a sepulcher, and in his bodily resurrection. Thus no one who refuses to believe in Christ’s resurrection can be saved.
The resurrection fulfilled His prophecies, as well as those of the Old Testament prophets, being the core message of the first century church and comforting the followers of Jesus in the following centuries, resulting in the adoption of Christianity as the predominant religion of the Roman Empire, in the 4th century. It was the essential doctrine of Protestant reformers, becoming crucial in the message that Biblical-based  churches preach today.
A renowned rationalist, Dr. Charles Guignebert, professor of History of Christianity at Sorbonne who utterly rejected Christ’s resurrection and His miracles in the New Testament, eventually reckoned that there would be no Christianity if belief in the resurrection had not been established. It was through that belief that the faith in Jesus and in His mission became the key element of a new religion that went on to take over the world.
The Christian faith is based on doctrines that depend in the physical resurrection of Jesus. Salvation by faith, justification and resurrection of those who believe, as well as the promise of Christ’s second coming, are evidence of that. That’s why those churches that discuss the resurrection on Easter Day and then forget about it the rest of the year are only preaching half of the Gospel.
Thus each convert is a “new creature in Christ,” and receives Christ as his Lord and Savior, believing in the resurrection and experiencing “the power of the resurrection” that enables him to live a full Christian life.