How do we know Christ's sacrifice is finished?

Hebrews 9:26 asserts that Christ appeared to put away sin by His sacrifice once for all. His declaration 'It is finished' signifies the completion of the work necessary for redemption, fulfilling all that was required to address humanity's sin. Unlike the Old Testament priests, who continually offered sacrifices, Christ’s one-time offering was sufficient and effective, underscored by the fact that He now sits at the right hand of God, a position denoting completion and authority over sin.