“The New is in the Old concealed, and in the New, the Old revealed,” claimed the fifth century theologian Augustine of Hippo, and he was right. Jesus Christ permeates the Old Testament from start to finish, as Jesus himself explained. “And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself” (Luke 24:27). The Scriptures “bear witness about me,” (John 5:39). Time and time again the Gospel writers narrate, or Jesus states, that “the Scriptures must be fulfilled,” and “Scripture cannot be broken” (John 10:35). The apostles taught people about Jesus “from the Scriptures,” (Acts 8:35; 18:28) and these “scriptures” are the (Greek) Old Testament. There was no “New Testament” at that time, for the documents which came to be acknowledged as new scriptures were still being written. The Old Testament contained the seeds of the gospel, and the apostles could explain who Jesus was, from its writings. “And Paul… reasoned with them from the Scriptures, explaining and proving that it was necessary for the Christ to suffer and to rise from the dead, and saying, ‘This Jesus, whom I proclaim to you, is the Christ’” (Acts 17:2–3).
Jesus is the seed of the woman who would strike the serpent’s head, the ark, the Lamb which God would provide, the promised son, the Passover lamb, the whole burnt offering, the High Priest, the serpent on the pole, the leader into the promised land, the kinsman-redeemer, the true king in the line of David, the Shepherd of Israel, the suffering servant, the Lion of the tribe of Judah, the Judge of all the earth, the Messenger of the covenant; God’s anointed, Immanuel God with us; the Saviour, who is Christ — the LORD. Jesus, who came from above, is above all (John 3:31–32). He is the image of God, all things were created by him, through him and for him, he is before all things and in him all things hold together, in everything preeminent (Col 1:15–19). Jesus is and always has been central to everything God has done and will do with creation. The Son is the means by which God created, and the means by which God redeemed that same creation and by whom God will indwell it.
But it wasn’t until Jesus had died and risen, completing his great redeeming act and sending his Spirit to his apostles, that the whole picture came together (John 15:26; 16:12–13). As Augustine said, the gospel was “concealed” (“latent”) within the Old Testament scriptures. It was there in types and shadows, in things the prophets and even the angels did not fully understand but which have now been revealed (1 Peter 1:10–12). It was not until the coming of the Son that the cornerstone of the building, the centrepiece of the great puzzle, was put in place. The treatise to the Hebrews on the incomparable greatness of the Son, surpassing angels, Moses, the Law and every other Old Testament type, opens with a statement of the final and complete revelation of God: “Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world” (Heb 1:1–2).
Until the advent of Jesus, the Old Testament could not be fully understood. Certainly, it told us a lot about ourselves and about God. It explains that God created us and how we fell into sin. It presents God as holy and righteous and emphasises our unworthiness to approach him. God established a covenant through his grace with a man whose descendants would become a great nation and from whom would come the Saviour. He redeemed that man’s descendants and chose them as his special people and gave them a Law by which there could be an exemplary theocracy on earth. When his people failed him, God chastised them and gave more and more clues to the final solution, a true King, prophet and priest who would bring the ultimate redemption and enable his spiritual people to be part of a world-wide and eternal kingdom. As the Old Testament saga unfolded, more and more was revealed about this great plan and the central figure, Jesus. For centuries the faithful in Israel looked for the direct intervention of God — and he finally came in the person of Jesus Christ. It was a progressive revelation. Abraham knew more about the promised son than Eve did. Moses had more detail on sacrifice and holiness than Abraham. King David understood more about his great Descendant than Abraham did. Isaiah filled out the awesome nature of the servant’s sacrifice. But until Jesus was revealed, these were just pieces of an incomplete puzzle. Only through Christ is God more fully known as Father, and as Son and as Holy Spirit. Benjamin B. Warfield expressed this in an apt metaphor:
The Old Testament may be likened to a chamber richly furnished but dimly lighted: the introduction of light brings into it nothing which was not in it before; but it brings out into clearer view much of what was in it but was only dimly or not at all perceived before… Thus the Old Testament revelation of God is not corrected by the fuller revelation which follows it, but is only perfected, extended and enlarged.” 
This picture is helpful because, on the one hand it upholds the inspired Old Testament as equally the Word of God, but at the same time puts it in perspective. We can learn a lot about God from the Old Testament, but not the whole story. The Bible uses the “fulfill” to encapsulate how the New Testament supersedes the Old, without contradicting or negating it. Consistently, the New Testament claims that Jesus and his work “fulfills” the Old Testament Scriptures. In English the word means to “fill fully,” in other words, to fill to the top, to complete what is lacking. The Hebrew words male and kalah and the Greek pleroo, teleo and their cognates mean the same; completeness and finishing. The Old Testament message is not a contradiction; it is incomplete. It becomes more complete as it journeys from Genesis to Malachi, but it remains incomplete until filled to the brim by Christ. That’s why Jesus was able to chide the disciples on the one hand for not understanding everything the Scriptures had said, but also to explain that he had come to more fully reveal the Father and fulfill (complete) all that was written. This concept also gives the lie to those who would force a dichotomy between the Old and New Testaments, between the supposedly wrathful and legalistic YHWH of Israel and the loving Father of Jesus Christ. It is only when we understand that the Old Testament is incomplete, not erroneous or contradictory in its message, that we can begin to understand its relationship to Christ and how the New Testament writers used the Scriptures.
There are two exegetical errors that can be made, and plenty of historical and contemporary examples of their making. Firstly, the Old Testament could be discounted, written off as contradictory or erroneous. The second century heretic Marcion did that; he posited that the Father of the Lord Jesus Christ was a different God from YHWH of the Old Testament and literally tore the Old Testament and every taint of “Jewishness” out of the Bible, accepting only an edited version of Luke and most of Paul’s letters. Early theologians  vigorously opposed Marcion, yet they also struggled with how to reconcile apparent contradictions between, say, the massacre of the Canaanites, and the God of love and mercy. One recourse was to allegory. Origen of Alexandria was (in)famous for his allegorising passages which seemed difficult in their literal sense, such as the battles of Israel. Whatever one’s knowledge and opinion of early Christian exegetical strategies, one thing is clear; they treated the text itself as revelation, a Christ-centred unity. For them, Jesus Christ is the basis for right reading of all of Scripture. If I may add an analogy of my own; Scripture is like a delicious, ripe orange. When sliced open its structure is revealed to be radial; each segment is oriented centrally, radiating outward and contained within a whole. Jesus Christ is not one slice among many, whereas portions of the Bible are. Jesus Christ is the whole, complete package, its radial arrangement. In a much misunderstood passage (Gal 3:24–25), Paul explains that the Law was a paidagogos, that leads us to Christ. The KJV unhelpfully translates this word as “schoolmaster,” implying that the Law is a teacher, and we can frame our understanding of God quite specifically through its precepts. That’s not what the word means, and it’s not what Paul is saying. The paidagogos (literally, child-leader) was a slave entrusted with the discipline of the master’s sons, ensuring that they did not play truant, but went to school and attended to their studies. It was a temporary and disciplinary role, subservient to the real Instructor, Christ.
Which brings me to the second error, as exemplified by an exegesis which takes a high view of Scripture, but a relatively low view of Jesus. This sort of exegesis is pear shaped, or bottom-heavy. Whilst not necessarily explicitly, it gives primacy to the Old Testament and forces the New Testament into alignment with the Old in a somewhat subservient manner. In its extreme, such an exegete says things like “The Trinity is not found in the Old Testament, so Jesus cannot be God.” The problem is, there’s a lot about God and Jesus and the Holy Spirit that isn’t explicit in the Old Testament, for reasons that have been explained above. But there is plenty of evidence of the God of the New Testament; loving Father, incarnate Son and poured-out Holy Spirit, in the Old Testament for those who have eyes to see (John 5:39-40). These are the things the New Testament clarifies and fulfills (completes). Examples include the extensive application of passages about YHWH to Jesus by New Testament writers, and application of appellations, characteristics and roles of God to the Lord Jesus. In contrast, a pear-shaped, or distorted Old Testament primacy approach models the New Testament on the Old, to make it defined by Old Testament limitations and squeezing Jesus into an inappropriate mould. It makes Jesus defined by and limited by, in a real sense, images in the Old Testament which are necessarily typological, shadowy and incomplete.
For example, sacrifice. God required sacrifice in the Old Testament. It was highly prescribed under the Law in minute detail, and laxity or abuse of the system was sacrilege. “For the life of the flesh is in the blood, and I have given it for you on the altar to make atonement for your souls, for it is the blood that makes atonement by the life” (Lev 17:11). The whole burnt offering, the Passover lamb, the sin offering, all typified Christ in some aspects. The blood symbolised the covenant and the covenants were sealed with blood (Heb 9:18–21). “Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins” (Heb 9:22). Jesus took up this imagery when he spoke of eating his flesh and drinking his blood (John 6:53–56), a saying which the disciples found difficult, doubtless because of their familiarity with sacrifices and the prohibition of eating blood. Jesus inaugurated his memorial supper with the words, “This is my blood of the covenant, which is poured out for many for the forgiveness of sins” (Matt 26:28). The apostles make it clear that Christ’s sacrifice, the shedding of his blood, brought salvation, drawing on the whole range of atonement metaphors; justification, redemption, reconciliation, access to God, sanctification (Rom 5:9; Eph 1:7; Col 1:20; Heb 9:12; 10:19; 13:12).
Undoubtedly, we can learn a tremendous amount about Jesus’ work on the cross from these pictures of atonement and sacrifice. But here’s the crucial thing: Jesus did not give his life because in the Old Testament God demanded blood for appeasement. God required blood sacrifice in the Old Testament to teach us that Jesus would give his life for us. Jesus did not have to die the way he did because he had to imitate the sacrifices of the Law. He died the way he did because that was God’s plan from before the world was created, and the Law (and pre-Law sacrifices such as in Gen 22) provided a framework for understanding that. Sacrifice was not unique to Israel; every ancient culture practiced it. It was part of the ancient mindset. Israel’s prescribed sacrifices were different because (a) they were made exclusively to the one God and (b) they were symbolic of something much greater and more permanent to come. Those sacrifices could never take away sin completely; they had to be offered continually, for specific sins. Only the sacrifice of Christ which actually destroyed sin itself could permanently deal with sin (Heb 9:11–15; Heb 10:4–10). In this way Christ fulfills the Law of sacrifice, not by simply being a better type of the same thing (a perfect man rather than a beast) but because this was always and only the efficacious sacrifice which would be made. Fulfilling means completing, finishing; it does not mean copying.
Why is this such a big deal? Because seeing the basis of Christ’s sacrifice as simply a better version of an ancient principle of blood atonement allows the person and work of Christ to be downplayed. “God requires blood and Jesus gave the best blood,” becomes the principle of atonement, rather than “God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life” (John 3:16). That is what “the life is in the blood” means.
Without that Christ-centred perspective, substitutionary atonement becomes a parody of justice. Jesus is just a man, albeit a perfect one, who is treated like a sheep or goat. How is that fair? How does that demonstrate the righteousness of God if Jesus is a mere man taking the place of mere men? Christadephians attack a straw man when they so misrepresent the atonement. Only when it is understood as God himself becoming flesh and blood for our sakes and averting his own wrath against sin by taking it upon himself in Jesus Christ, as planned from before Creation, does substitutionary atonement work. It is no mere “exemplary” death by means of which we are shamed into an “apology”  but a gracious act of redemption. “Sacrifice” is the type, not the principle, of atonement. But if one denies Jesus is God, then one is forced to reject substitutionary atonement. If one uses a pear-shaped exegesis of Jesus’ sacrificial work, defined by Old Testament types, this will lead to a denial of the efficacy and meaning of substitutionary atonement and the very notion of Who Jesus is.
Such distorted interpretations also lead to ridiculous ideas such as a need for continuing animal sacrifices in the Kingdom of God. This latter, perpetuated by a pear-shaped exegesis of Ezekiel’s temple prophecy (Ezek 40–48) forces Jesus into the rather subservient role of “prince” and the Kingdom as merely an eternal perpetuation of a superseded theocracy. The ancient kingdom of Israel was an incomplete and imperfect type of the people of God, being ruled by succession of sinful kings who at best only typified God’s eternal King. Israel was never the last word as God’s people and should not be used to limit the concept of God’s kingdom and people. The type that was the Davidic kingdom needed to be full-filled in the true reign of God, in Christ. But by viewing Old Testament Israel with its laws and constrained access to God as paradigmatic rather than symbolic, we end up with a model of the ekklesia that is also constrained by rules and legalism and by a low view of Christ. This model presumes the Kingdom (more correctly, the word basileia means “reign”) of God cannot be present in any sense now, because we don’t see a literal kingdom on earth. That has to wait, in its entirety, until Jesus returns and builds the temple of Ezekiel’s prophecy. This model makes the Old Testament’s limitations and incompleteness define how we view the New Testament, rather than allowing the New Testament to put the Old into perspective. It is forcing Jesus Christ, King of kings and Lord of lords, into a mould that makes him just a better version of one of Israel’s kings. The New Testament does not deny any continuity of the old kingdom of Israel with God’ eternal kingdom, but sets it in context as a temporary model. The eternal reign, or kingdom of God has been inaugurated by the coming of the Lord Jesus, and there is now neither Jew nor Greek and people out of all nations are being drawn to him (Rom 10:12–13; 11:25–27; Gal 3:28–29; 1 Peter 2:9–10). Certainly, that reign is still to be consummated, but in that full realisation of it, there will be “no temple in that city, for its temple is the Lord God Almighty and the Lamb” (Rev 21:22).
Jesus defines the Old Testament types; they do not define or limit him. Christ is the end of the law for righteousness to everyone who believes (Rom 10:4). Jesus revealed more about himself, the Father and the Holy Spirit than the Old Testament could, but the traces are there, for they testify to him. Jesus fulfilled — completed — the Scriptures; they did not define or complete him. Scripture did not paint him into a corner or constrain him; it was a preview for what he came to do, his eternal grand design, revealed piece by piece. God completed the work begun at creation, “making known to us the mystery of his will, according to his purpose, which he set forth in Christ as a plan for the fullness of time, to unite all things in him, things in heaven and things on earth. In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will” (Eph 1:9–11).
- Augustine, Questiones in Hepateuchum http:www.augustinius.it/latino/questioni_ettayeuco/index2.htm
- Warfield, Benjamin B. Biblical Doctrines. repub. Edinburgh: Banner of Truth, 1988, 141–142.
- The classic polemic, Against Marcion, was written by Tertullian c.208 AD http://www.newadvent.org/fathers/0312.htm
- John J. O’Keefe and R.R. Reno, Sanctified Vision: An Introduction to Early Christian Interpretation of the Bible. Baltimore: John Hopkins UP, 2005. Particularly chapter 2, “Christ is the End of the Law and the Prophets,” 24-44.
- Which is how Robert Roberts defines the atonement in The Blood of Christ, 1895. repr. Birmingham: The Christadelphian, 2006.