How do we know the atonement of Jesus is effective?

The effectiveness of Jesus' atonement is supported by multiple scripture passages that indicate it was a definitive sacrifice for His people. For example, Hebrews 10 states, 'Their sin and their iniquity will I remember no more,' emphasizing that His sacrifice effectively put away sin. Additionally, John 10:15 reveals that Christ lays down His life for His sheep, indicating a specific group for whom He atoned. The notion that Jesus died for all men universally contradicts the effectiveness of the atonement, as it would imply that some for whom He died could still perish, which is inconsistent with God's redemptive plan. Therefore, the scriptural assertion is that His blood is powerful, cleansing all whom He came to save.