Christ has obtained a ministry that is as much more excellent than the old as the covenant he mediates is better, since it is enacted on better promises. ( Hebrews 8:6 6 But now hath he obtained a ministry the more excellent, by so much as he is also the mediator of a better covenant, which hath been enacted upon better promises. )

Christ is the Mediator of a new covenant, according to Hebrews 8:6 6 But now hath he obtained a ministry the more excellent, by so much as he is also the mediator of a better covenant, which hath been enacted upon better promises. . What does that mean? It means that his blood — the blood of the covenant ( Luke 22:20 20 And the cup in like manner after supper, saying, This cup is the new covenant in my blood, `even' that which is poured out for you. ; Hebrews 13:20 20 Now the God of peace, who brought again from the dead the great shepherd of the sheep with the blood of an eternal covenant, `even' our Lord Jesus, ) — purchased the fulfillment of God’s promises for us.

It means that God brings about our inner transformation by the Spirit of Christ.

And it means that God works all his transformation in us through faith in all that God is for us in Christ.

The new covenant is purchased by the blood of Christ, effected by the Spirit of Christ, and appropriated by faith in Christ.

The best place to see Christ working as the Mediator of the new covenant is in Hebrews 13:20 20 Now the God of peace, who brought again from the dead the great shepherd of the sheep with the blood of an eternal covenant, `even' our Lord Jesus, –21:

Now may the God of peace who brought again from the dead our Lord Jesus, the great shepherd of the sheep, by the blood of the eternal covenant [this is the purchase of the new covenant], equip you with everything good that you may do his will, working in us that which is pleasing in his sight, through Jesus Christ, to whom be glory forever and ever. Amen.

The words “working in us that which is pleasing in his sight” describe what happens when God writes the law on our hearts in the new covenant. And the words “through Jesus Christ” describe Jesus as the Mediator of this glorious work of sovereign grace.

So, the meaning of Christmas is not only that God replaces shadows with Reality, but also that he takes the reality and makes it real to his people. He writes it on our hearts. He does not lay his Christmas gift of salvation and transformation down for you to pick up in your own strength. He picks it up and puts in your heart and in your mind, and seals to you that you are a child of God.