What does it mean that Christ will not fail?

The phrase 'He shall not fail' signifies the absolute certainty and success of Christ's redemptive work. Isaiah 42 declares that Jesus will accomplish God's will and justify His chosen ones, asserting His effectiveness as a Savior. Unlike a savior who could potentially falter, Jesus’ mission is assured by God's sovereign decree. This assurance brings hope and comfort to believers, affirming that all for whom Christ died will be saved, grounding faith in the efficacy of His atoning work. Therefore, we are to trust that He will fulfill all His promises completely.