How do we know that Christ's sacrifice provides assurance of salvation?

In the sermon, it is made clear that our assurance of salvation is rooted in the work of Christ rather than our own efforts or good works. The passage from Hebrews 10 highlights that through Christ's sacrifice, believers' hearts are sprinkled clean from an evil conscience, and their bodies washed pure, affirming that they can approach God with confidence. This assurance is important as it distinguishes between faith in our works versus faith in Christ's completed work, demonstrating that our standing before God is secure because of His faithfulness.