How do we know atonement through Christ is true?

The truth of atonement rests on the sufficiency of Christ's sacrifice, as noted in Hebrews 9:26, which affirms that Christ has 'once in the end of the world hath he appeared to put away sin by the sacrifice of himself.' This act transcends the Old Testament rituals, which served only as types and shadows of the true Atoner. By His death and resurrection, Jesus fulfilled the requirements set forth in the law, thus establishing a new covenant rooted in grace and faith, providing believers assurance of their redemption and justification before God.