Jesus demonstrates the truth of who he is by what he does in the present. That is why the message of salvation through Jesus Christ is accompanied by a demonstration of God’s saving power.
Jesus’ resurrection and ascension to the throne of heaven is an integral part of the gospel. He preached about the Kingdom of God, which means the reign of sin and death is broken and a new reign by a new sovereign, a new King, has begun. And the same power that raised Christ from the dead is now at work in all who believe in his name.