How do we know Jesus' sacrifice was sufficient?

The sufficiency of Christ's sacrifice is demonstrated by His fulfillment of the eternal covenant established by God the Father. When Jesus uttered the words 'It is finished,' recorded in John 19:30, He completed the work that was required for the salvation of those given to Him by the Father. This victory over sin and death signifies that nothing else is needed for redemption, as His blood provides the full payment for sin.

Furthermore, Hebrews 9:12 confirms that Christ, as our great high priest, entered into the heavenly sanctuary with His own blood, having obtained eternal redemption for us. The biblical narrative, particularly in the Old Testament, illustrates through various types and shadows how the sacrificial system pointed towards the ultimate sacrifice of Christ. His life, death, and resurrection validate the sufficiency of His sacrifice, assuring us that all those for whom He died are eternally secure in Him.