“Behold, I have come;
in the scroll of the book it is writtenof me:
I delight to do your will, O my God;
your law is within my heart.” (Ps. 40:7-8)
You have kept count of my tossings;
put my tears in your bottle.
Are they not in your book? (Ps. 56:8)
A Christological Understanding of Psalms 40, 56, & 139
[Read: Psalms 40, 56, & 139]
Among those doctrines most hated by the enemies of the Gospel is the doctrine of Christ’s active and passive obedience. This glorious truth eliminates man from the work of salvation, placing all of the emphasis on what God has already done for His people. As Berkhof explains:
Christ as Mediator entered the federal relation in which Adam stood in the state of integrity, in order to merit eternal life for the sinner. This constitutes the active obedience of Christ, consisting in all that Christ did to observe the Law in its federal aspect, as the condition for obtaining eternal life…His passive obedience consisted in His paying the penalty of sin by His sufferings and death, and thus discharging the debt of all His people.
Thus, the importance of our Lord’s active and passive obedience can be clearly seen, for “by His obedience and death Christ paid in full the debt of all those who are justified…He fully and absolutely satisfied all the claims which God’s justice had upon them.” To deny this doctrine, therefore, is to remove the grounds of our justification before God, and to not understand the work of our Lord Jesus. So when we hear our Lord tell us that the Scriptures all testify about Him, meaning His life, death, burial, resurrection and ascension, we should listen to Him and, resultantly, be wary of those who seek to contradict Him. Of course the entirety of the details given in the New Testament regarding the Person and Work of Christ are not so explicitly given to us in the Old Testament; however, they are seminally present in the Old Testament in varying degrees.
As I’ve shown elsewhere, in the book of Psalms the doctrine of dual imputation is contained when we look at Psalms 31 and 32 in light of our Lord’s Person and Work. Psalm 31 reveals Christ to us as Suffering Servant and Perfect Atoning Substitutionary Sacrifice to whom the sins of God’s elect have been imputed. Psalm 32, on the other hand, reveals that the sins of God’s elect are not imputed to them; instead, the righteousness of God is imputed to them by the instrument of faith. Consequently, I don’t think it is assuming too much to believe that the seeds of the doctrine of the active and passive obedience of our Lord Jesus can be found in the book of Psalms. And I believe that when we compare Psalms 40, 56, and 139, we see that this is quite clearly the case. In each of these Psalms, we come across a reference to God’s Book, a Book which contains three things: (i.)the coming of the Lord Jesus and His perfect obedience to the Father’s will, (ii.)the suffering of the innocent Servant of the Lord, and (iii.)the entirety of the life of God’s Beloved Son, formed by His Spirit in the womb of a woman. Assuming that this “Book” is the same in each instance, which it may or may not be, what we learn is that Christ, whose entire life is the subject of God’s Book, is formed by the Spirit of God, He then lives a life of perfect obedience (as the Lord’s Book says that He will), only to suffer unjustly at the hands of wicked men. He is, however, delivered from death, just as the apostle says in Hebrews 5:7: “In the days of His flesh, Jesus offered up prayers and supplications, with loud cries and tears, to Him who was able to save Him from death, and He was heard because of His reverence.”
The three mentions of God’s “Book” seem to speak prophetically about the Lord Jesus’ sinless conception, perfect life of obedience, and substitutionary sacrifice for our sins. While “the Book” of God foretells Christ’s perfect obedience in Ps 40, it also foretells Christ’s suffering for our sins in Ps 56; and both His active obedience (Ps 40) and His passive obedience (Ps 56) are the subject of God’s Book which speaks to these things (Ps 139). When our Lord Jesus tells us that “the Scriptures” “bear witness of [Him],” that Moses wrote of Him, indeed that “all the prophets” spoke of His suffering, death, resurrection, and the subsequent preaching of repentance and the forgiveness of sins, we should take note and understand that He is not speaking hyperbolically. David, one of the prophets, in his psalms points us beyond himself, beyond ourselves, and reveals Christ to us as God’s Elect Son, formed by the Holy Spirit of God, Obedient Son of whom the Book Prophesies, and the Servant of God who suffers at the hands of His enemies but is eventually vindicated by God delivering Him from death.
These psalms taken in conjunction with one another tell us the story of our Lord Jesus; they reveal the Gospel to us in very clear terms. Perhaps David had an inkling of understanding regarding what he was inspired to write. Perhaps he saw his psalms as having no further, ultimate referent; perhaps he did. Either way, we can say confidently, I think, that the seeds of one of the most, if not the most important doctrine is contained in the Old Testament. The doctrine of the active and passive obedience of our Lord Jesus Christ was not invented during the Reformation, nor has it been imposed upon Scripture. Rather, it is a doctrine that is firmly rooted in the Old Testament and which finds clear exposition in the New Testament.
 Systematic Theology, pp. 380-381
 The 1689 London Baptist Confession of Faith, p. 33
 Cf. Ps 40:6-8
 Cf. Ps 56:8
 Cf. Ps. 139:16
 Cf. Ps 56:13
 Cf. John 5:39
 Cf. John 5:46-47
 Cf. Luke 24:13-49