Some thoughts from 1 Corinthians 15:1-19-
People believe that Jesus’ death is the reason we have eternal life. That death was the death we should have died because of our sinfulness. However, it's his resurrection that gives us the eternal life we have been promised. Paul is reminding the Corinthian church about this message he had preached- one that they all believed in, and that if they do not hold firmly to it, their faith is all for nothing. Putting faith in Christ and His resurrection is not something to be taken lightly. If the Holy Spirit lives within you, then you really believe that Jesus was and is the redeemer for our sin. This is not something you can take back, and if you think it can be taken back or taken away, then you never had it in the first place. That is why Paul says to hold firmly to it, or els you have not really believed.
Paul gives all the further proof that they and we should need to continue in our faith- that according to all we put our faith in, the Holy Scriptures, Jesus carried out what was written. He then goes on to tell the testimony of those who had seen him after death to give further proof of a resurrection, and through that resurrection of Jesus, we receive new life. Paul also gives a little of his testimony before he followed Christ, and how undeserving he was of God's favor. But, since receiving new life, he worked all that much harder to prove he deserved God's gift.
Those who do not believe in any resurrection and keep Jesus on the cross as a martyr are not preaching a full Gospel message, and if Jesus is really just a dead person and not raised to life, then we are worse off than anyone else- we still live in our sin thinking we are forgiven. Praise God that Jesus came to put an end to spiritual death through His death and resurrection. From that resurrection, we get new life and full connection to God.
So, Jesus raised to new life or not? You cannot believe half the Gospel- that Jesus took our punishment physically but was not raised to life after death. The resurrection is what gives us proof that we have been forgiven through that death. Anyone can give their life to take punishment for someone else. God proved that He has forgiven us through Jesus’ death by raising him from death, and now we have the ability to be raised from spiritual death.