We must realize that our own personal sin is what necessitated Christ's death. And only by repenting of our sins and being reconciled to God by the death of Christ can we be assured of eternal life (Acts 2:38; John 5:29; John 11:25).
This is not to minimize the importance of Christ's resurrection. It, too, is a crucial step in the salvation process (1 Corinthians 15). After being reconciled to God the Father by the death of His Son, ultimately we are saved by Christ's life as He pleads for us in the role of our High Priest and lives in us through the Holy Spirit, helping us to overcome sin (Romans 5:10; Hebrews 4:14-16; 1 John 2:1; Galatians 2:20). The process of our coming out of sin is pictured in the biblical feast immediately following Passover, the Days of Unleavened Bread, during which Christ's resurrection occurred.
Yet the Bible nowhere instructs Christians to keep a special celebration of Christ's resurrection like Easter, nor is there a biblical record of early Christians doing so. Instead it's clear that both Jesus Christ and the apostle Paul expected Christ's followers to commemorate His sacrificial death on our behalf in a special ceremony (Matthew 26:26-28; 1 Corinthians 5:7; 1 Corinthians 11:23-28).
Nonetheless, the celebration of Easter prevailed. Those who remained faithful to Christ's example of keeping the Passover and the Days of Unleavened Bread decreased in number and were persecuted by those favoring Easter.