How do we know Jesus' redemptive work is complete?

In John 19:30, when Jesus proclaimed 'It is finished,' He announced the completion of the redemptive work that the Father sent Him to accomplish. This declaration signifies that every requirement of the law was fulfilled and that the ultimate sacrifice for sin was made, thereby satisfying the justice of God on behalf of sinners. The resurrection of Christ further assures believers of this completed work, as it validates His sacrifice and victory over sin and death. This underscores that there is nothing left for us to do to achieve reconciliation with God; we rest in the sufficiency of Christ's atonement alone for our salvation.