How do we know that Christ's sacrifice was effective?

Christ's sacrifice is deemed effectual because it not only secured our atonement but also guaranteed our resurrection and justification. As noted in Romans 4:25, Christ was raised for our justification, signaling that His death was not merely an act of love but a completed work that satisfied divine justice. Paul stresses that the resurrection validates His sacrifice, affirming that God accepted His offering as sufficient for the sins of His people. Therefore, believers can rest assured that Christ's work secures not only our forgiveness but also our eternal inheritance as co-heirs with Him, which is rooted in the unwavering promise of God.