How do we know Christ's death was effectual?

The effectual nature of Christ's death is primarily established through His resurrection, which serves as God's confirmation that His sacrifice was accepted. As stated in the sermon, when Jesus declared 'It is finished' on the cross, He signified that the payment for sin was fully made. Furthermore, the effectiveness of His atoning work is reflected in the ongoing transformation and salvation of sinners through the preached gospel. This historical and ongoing fruit of the gospel attests to the reality of an effective substitutionary atonement for the elect.