How do we know Jesus' work on the cross is sufficient?

In the context of the sermon, when Jesus proclaimed, 'It is finished,' He signified the fulfillment of all the redemptive plans of God, ensuring that His sacrifice was entirely sufficient for the atonement of sin. The completion of His work guarantees acceptance before God for those who believe, as expressed in Hebrews 4:14-16, where we are encouraged to come boldly to the throne of grace, assured of mercy and help in time of need. The shed blood of Christ not only purchased redemption but also secured our eternal relationship with God, eliminating the bondage of sin and the devil's influence.