The resurrection of Jesus Christ from the dead does not exempt us from confessing our sins, the resurrection of Christ keeps our confessing of sins from being futile.
Without the truths of Easter maybe the most pitiable part of our Lord’s Day liturgy would be the assurance of pardon. A call to worship could still come from any bigger-than-man god. Such a god could also demand our prayers and our obedience to whatever instructions given. Gods like sacrifices, and if they can be pleased they may give support to the worshippers. But only one God gives forgiveness, and there is no forgiveness without death, and there is no complete forgiveness without resurrection from death.
“If Christ has not been raised, then our preaching is in vain” (1 Corinthians 15:14). “If Christ has not been raised, your faith is futile and you are still in your sins” (1 Corinthians 15:17). “If in this life only we have hoped in Christ, we are of all people most to be pitied” (1 Corinthians 15:19).
But by the resurrection of Jesus we know that He is God (Romans 1:4). Easter declared Him so. By the resurrection of Jesus we are born again into a living hope (1 Peter 1:3). It is of first importance, not only that Christ died for our sins and that He was buried, but also that He was raised on the third day in accordance with the Scriptures (1 Corinthians 15:3-4).
The cross by itself does not prove forgiveness, the cross shows the offensiveness and cost of our sins. The empty tomb proves that God accepted Christ’s sacrifice and that He accepts us in Christ.