How do we know that Christ's work secures our salvation?

The foundation of our assurance lies in the understanding that Christ is our surety and substitute. In Galatians 4:4-5, we learn that God sent His Son to redeem those under the law so they could receive adoption as sons. Moreover, 1 John 1:9 assures us that if we confess our sins, He is faithful and just to forgive us our sins. Thus, the assurance stems from Christ's intercessory role and the divine promises secured by His blood, which not only makes salvation possible but certain for all whom the Father has given to Him before the foundation of the world.