Why is believing in Christ important for Christians?

Belief in Christ is central to the Christian faith, as Jesus Himself states, 'This is the work of God, that you believe in Him whom He has sent.' This doctrine emphasizes that eternal life is a gift from God received by faith in Jesus. The foundational truth is that Jesus not only provides our salvation but sustains it. The sovereign grace theology affirms that God's choice to extend grace is unmerited and not based on human efforts or righteousness. Hence, real Christian life is lived actively in faith, recognizing that any progress or good deed results from Christ's active work in the believer.