How do we know that Christ's death was effectual?

The effectual nature of Christ's death is underscored in Matthew 1:21, which states that He will save His people from their sins. This declaration reveals that Jesus’ sacrifice was purposefully designed to secure the salvation of the elect, implying that it does not merely make salvation possible but accomplishes it for those whom He died. Additionally, John 10:14-15 highlights that Jesus, the good shepherd, lays down His life for the sheep, further emphasizing that His redemptive work is not arbitrary but aimed at a specific people whom God has chosen before the foundation of the world (Ephesians 1:4). Therefore, believers can rest assured that Christ's death effectively secures their salvation.