Is The Cross Of Christ The Most Important Part Of The Plan Of God?
The cross is a key and critical part of God's plan for the redemption of mankind. But it is incomplete without the incarnation, the perfect life of Jesus, and the resurrection and ascension. In the sermons in the book of Acts, the apostles talked more about the resurrection than they did about the crucifixion.
If Jesus had not been God, his death on the cross would have meant nothing. (Hence the importance of the incarnation)
If Jesus had sinned, then his death on the cross would have meant nothing. (Hence the importance of His perfect life)
If Jesus had not risen, then we would still be in our sins. (Hence the importance of the resurrection)
But if Jesus had not died, there would be no atonement for sin. (And the same for any of the above three scenarios - there would be no atonement for sin.)