Why is it important for Christians to see Christ as their sanctification?

In Hebrews 10:10, it's stated, 'By that will we have been sanctified through the offering of the body of Jesus Christ once for all.' Sanctification is integral to the believer's life, as it reflects the work of Christ in making us holy. Many professing Christians mistakenly believe that sanctification is a joint effort, where Christ’s sacrifice must be supplemented by their efforts. However, true believers understand that Jesus is our complete source of holiness and purity. He fulfills the law's requirement perfectly, and by His Spirit, we are enabled to live out this holiness in our daily lives, without relying on our works.