Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah: Not according to the covenant that I made with their fathers…for this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people: And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest. (Heb. 8:8-12)
There are a number of ways to describe the difference between the Old Covenant and the New Covenant. Some people would say that the Old Covenant is one of law, while the New Covenant is one of grace. There is some Truth to this. But if you gather up all of God’s Words on this matter, perhaps the best way to say it is this: The Old Covenant was a shadow of Christ. The New Covenant is Christ Himself – IN US.
All through the OT we see Christ in type and shadow. Circumcision pictures Christ crucified. The Passover Lamb is a type of Christ. All of the offerings and sacrifices show Christ, in one dimension or another, in His Redemptive work. The High Priest is a type of Christ, as are the Levites. The Tabernacle is Christ. The Holy of Holies is Christ. The moral law itself was a written expression of the righteousness of God through Christ. Indeed, Hebrews says, “For the law having a shadow of good things to come, and not the very image of the things…,” (Heb. 10:1). and Paul affirms, “which are a shadow of things to come; but the substance is of Christ.” (Col. 2:17)
All of these types and shadows were gathered up into John the baptist, and were collectively only, “a voice crying in the wilderness,” preparing the way of the Lord. (Is. 40:3) The law, “was our schoolmaster to bring us unto Christ, that we might be justified by faith. But after that faith is come, we are no longer under a schoolmaster.” (Gal. 3:24-25) The shadow of Christ has now given way to Christ Himself. We are no longer UNDER the OT. Rather, Christ is IN US.
If you read the above passage from Hebrews you will note that the distinction that is given between the Old and New Covenants is that of the OUTWARD under the Old vs. the INWARD under the new. This agrees with Jesus’ words to His disciples before His ascension. He said, “The Holy Spirit has been WITH you, but shall be IN you.” (John 14:17) Under the Old Covenant the Spirit of God made many visitations. God was WITH people by His Spirit. But under the New Covenant, Jesus Christ, through the Spirit of God dwells IN US.
This New Covenant is Christ in us – (Col. 1:27) — in Christ we are birthed a new creature in Jesus Christ. It is the Covenant of full Redemption for those who will embrace Christ, and of the full restoration of all creation under God. Christ will be all in all.
Christ in us had never been before Acts 2 — as noted, Jesus said so. But Paul also says, “Even the mystery which has been hid from ages and from generations, but now is made manifest to his saints: To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory.”