"We have seen with our own eyes and now testify that the Father sent His Son to be the Savior of the world" (1 John 5.14).

John is saying also that there were others who saw Jesus resurrected. Salvation requires resurrection, because to only be forgiven for your sins by accepting the blood without a next step would be pointless. Forgiveness, a being cleansed by God and made presentable to Him, leads to the next step which is eternal life through resurrection by the resurrection of our Lord Jesus Christ.

Christians have resurrection life even now, a foretaste of the day of resurrection together.