Why is the promise of Christ's success in saving important for Christians?

The promise of Christ's ultimate success in saving is foundational for the faith of believers. It reassures us that our salvation is not contingent upon our efforts but solely upon the completed work of Christ. As seen in 1 Peter 1:4-5, believers are provided with 'exceeding great and precious promises' that affirm our participation in the divine nature, having escaped the corruption of the world. Knowing that Christ shall not fail instills confidence in evangelism, as we trust that He will draw His chosen people to Himself in accordance with God's sovereign plan.