How do we know Jesus' sacrifice at the cross is sufficient?

The sufficiency of Jesus' sacrifice is grounded in his perfect obedience to God's law. In John 17:4, Jesus declares, 'I have finished the work which thou gavest me to do,' confirming that His atoning work is complete and perfect. He lived a sinless life, fulfilling all that the law required. By taking our place on the cross, he satisfied divine justice for sinners. His resurrection is the ultimate confirmation of the efficacy of his sacrifice, demonstrating that he has conquered sin and death for those who believe.