It seems odd that we sometimes stop in our thinking (and our theology) after 1 Corinthians 15:3, “Christ died for our sins according to the Scriptures.” It’s tempting to think of the resurrection as the icing on the cake, something nice and sweet but not essential. When reading the New Testament and particularly the gospels, it’s hard to mistake that the death of Christ is foundational for understanding Jesus’ ministry and the gospel. What about the resurrection? The central part of Paul’s discussion of the resurrection in 1 Corinthians 15 makes the point that it is indispensable. Believers have the assurance that our sins are forgiven because Christ has been raised:
Paul’s point, however, is the crucial one that the death, by itself, is not sufficient to deal with sins; he goes on to say, “if Christ has not been raised, your faith is futile; you are still in your sins” (1 Cor. 15:17). From what follows, it is clear that human beings are delivered from the death that Paul regards as the wages of sin through being raised to a new life, in the same way as Christ was raised (1 Cor. 15:21–22). Moreover, this resurrection of believers is not simply like Christ’s resurrection, but it comes about through their being united with Christ. Here, then, it is made absolutely clear that the death of Christ would have no saving efficacy apart from his resurrection.
—I. Howard Marshall, Aspects of the Atonement: Cross and Resurrection in the Reconciling of God and Humanity
Christ is risen, sins are forgiven, Christ is risen indeed!