(After John Flavel's citation of Ps.36.9, in his excellent work of the same name)

'He that believeth on the Son hath everlasting life:
and he that believeth not the Son shall not see life;
but the wrath of God abideth on him.'
John 3.36

Testimony to the same doctrine from Jewish scripture, despite Jewish denials.
'I neither learned wisdom, nor have the knowledge of the holy.
Who hath ascended up into heaven, or descended? who hath gathered the wind in his fists?
Who hath bound the waters in a garment?
Who hath established all the ends of the earth?
What is his name, and what is his son’s name, if thou canst tell?
Every word of God is pure: he is a shield unto them that put their trust in him.
Add thou not unto his words, lest he reprove thee, and thou be found a liar.'
Proverbs of Solomon 30.3-6    
(from the Jewish Tenach, textually identical to the Christian Bible's Old Testament, despite subsequent Jewish apostacy from the doctrine of Sonship)

Only Begotten and Firstborn
- dual aspects of the Sonship of Christ.

'...They shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his

only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn.' Zech.12.10c

The eternal and unique Sonship of Christ, His partaking of the full substance of Deity is the vital foundation of our faith. It is undermined by Arians and Socinians, and completely denied by other monotheistic faiths. Muslims like most modern day Jews not only deny the Divine Sonship of Jesus Christ, they deny such a concept is possible. (This betrays Islam’s roots, a sterile hybrid of Arab fertility cults and a radical denial of the likeness of God to His created image in man (Gen.1.27, Acts 17.28,9), a denial inspired by a philosophical¹ backlash to idolatry, which it still shares with and probably drew from Hellenised, anti-Messianic Judaism.) Yet the Holy Scriptures, to which these groups pay lip service, bear impregnable witness to this kernel truth of God's revelation.

4Q246: A manuscript in cave 4 among the Dead Sea Scrolls, bearing witness to pre-Messianic use of the term 'Son of God' for the Messiah.

David insists, 'Kiss the Son², lest he be angry and ye perish from the way'. Solomon's Agur asks of the Creator, 'What is His name, and what is His Son’s name, if thou canst tell?'³ John the Beloved declares this is the sacred watershed, 'He that hath the Son hath life; and he that hath not the Son of God hath not life'. Our success or failure in grasping this point reveals our whole relationship to the living God, 'Whosoever denieth the Son, the same hath not the Father: (but) he that acknowledgeth the Son hath the Father also.' The Spirit twice reveals in the Gospels that the Son is the exclusive key to the Father, 'No man knoweth who the Son is, but the Father; and who the Father is, but the Son, and he to whom the Son will reveal him.' May the Father guide us by His Spirit to know Him in His Son.

A lightning survey of the Apostle John's epistles anchors the absolute and explicit centrality of Christ's Sonship to Scripture. The Son is only agent of our fellowship with His Father (1 Jn.1.3), the Son’s blood alone avails for sin (v.7), and the Father heeds only His effective advocacy when we stumble (2.1). The Son is the essence of Truth (2.22), denial of His Sonship the essence of  heresy (2.23), affirmation of the Son is the true apprehension of the whole Godhead (2.23, 2 Jn.9), and continuance in professing the Son the foothold of perseverance (1 Jn.2.24). The Son’s manifestation destroys Satan’s work (3.8), faith in His Son is the essence of Divine law (3.23), the Son best reveals God’s love and alone propitiates our sin (4.10). The Son is the sent Saviour of the world (4.14), and the Son is the keystone of our testimony, the means of God’s indwelling us and ours in Him (4.15). The Son is our victory over the world (5.5), the Son the focus of God’s witness to us (5.9), the fulcrum of true faith in and familiarity with God (5.10), and the denial of the Son the blaspheming of God’s character and record (5.10). As related, the Son is the ultimate watershed of life (5.11,12). Faith in the Son Himself is the purpose of revelation, and both the means and outcome of growth in assurance (5.13).  Growing appreciation of Christ’s Sonship is the only root of healthy assurance and of progress in understanding the true God Himself, Who is known only in His Son (5.20). As with the rest of scripture, much more evidence lies implicit in the context than is here surveyed. How then can even the meanest, true disciple disregard grasping the doctrine of the Son to progress in godliness?

There is an absolute distinction between the only begotten Son, Christ’s unique eternal Sonship, and His specially acquired status as the Firstborn, implying potential, successive siblings in the same order, though  not of the same dignity. Arians commonly confuse the two in order to denigrate the Son. Jehovah’s Witnesses claim for example that Col.1.15 proves that Christ is the first and highest ranking created being. They suppress the evidence of an acquired primogeniture for the second born Ephraim, or the late born Joseph (Gen.48.20, Jer.31.9, 1 Chr.5.2), or the express declaration of the Father, ‘I will make Him my firstborn’, of a Beloved who evidently was not born first (Ps.89.27).

For a mere man, being a solitary child and bearing title to the firstborn is no marvel. Indeed the term only begotten (monogenev in the Greek NT, dyxy in Hebrew) is applied to the widow of Nain’s only son, who alone could be the firstborn (Lk. 7.12), as it is to Isaac (Gen.22.2, Heb.11.17) who was also confirmed as lawful heir and firstborn, at Ishmael’s dispossession. (The Septuagint translators blur the distinction by beautifully distilling the term as ‘beloved’.)

However for the Divine Son, Whose relation with the Father is both singular and eternal (Jn.1.18) also to bear the title of firstborn (rwkb  in Hebrew, prototokov in Greek) is startling. How could the unique Sonship of Christ be in any degree shared with worms?

Nevertheless in the intriguing verse before us, Zech.12.10, the Hebrew terms for both aspects of Christ’s Sonship appear intertwined. The text echoes others of a uniquely bitter but vital realisation (Jer 6.26-7, Am 8.9-10). This is the One Who is pierced, Occasion of the outpouring of the Spirit of grace, Author of the text, and Opener of the Fountain of cleansing - the mourning for this Son of David, is as mourning for both the unique and the firstborn (there are no possessives, but the articles are both definite in the original).

John also testifies to the dependence of a believer’s adoption as son on the exclusive Divine Sonship of Christ. He marvels at this gift and explains how it may be discerned (1 Jn.3.1-3), but the gift is based on promises that depend on the Son, (2.24-5), as is the efficacy that establishes its genuineness (3.7-9). To leave us beyond doubt that our sonship is contingent on Christ’s eternal Sonship, he shows the spring of the essence of our filial nature rests entirely in God’s prior display of love in His only begotten Son (4.7-10, 5.1, 4.19-20). Being enabled to emulate this love is the major principle of a healthy assurance that we are indeed adopted (3.14,19). A similar linkage between Christ’s distinctive Sonship and our adoption is found in the Gospel of John, His own received Him not, but He gives power to become the sons of God (1.12), Who is Himself the only begotten Son, full of grace and truth (1.14) and Who is in the bosom of the Father (1.18), yet declaring Him.

So when and how is this linkage established? The theme of the Firstborn is a rich and deep one in scripture. For example, whilst Reuben is Jacob’s natural firstborn, as we saw, he is replaced formally by Joseph (1 Chr.5.2); though in Jacob’s blessing, to our surprise, it is Judah who fulfils the promise of Joseph’s dream (Gen.49.8), and to whom his brethren prostrate themselves and praise. There is one later, unexpected surprise from yet another son. The offering of the firstborn becomes the foundation stone of the priesthood and all Levi’s tribe must be taken as their representatives before God (Num.3.12-13). The substitution is so precise that the numerical deficit must be redeemed exactly (Num.3.44-51). The exchange is consecrated in the manner of a sacrifice, the people of Israel laying hands on the Levites, who are offered to the Lord for service (Num.8.10-11). This is explicitly stated to be in place of the redeemed firstborn, (v.17-18) and so that they may ‘make an atonement’ (v.19).

So there is a priestly connexion to the firstborn, though its usual sense was as legal title to the family inheritance. The firstborn son of a despised wife is not to be capriciously denied this title (Deut.21.15-7), and this was the root of Esau’s fury at his doubly usurping brother (Gen.27.36).

So how has our Lord Jesus Christ become the firstborn to us? How is His incomparable Sonship inextricably bound to ours?

The Greek term for firstborn (prototokov) is used 9 times in the NT, twice of virgin Mary’s firstborn son. Christ is the Son of God and also the Son of man, but neither of these glorious filiations sufficiently explains the link. For this we may draw a hint again from our text, where the shadow of the cross is unmistakeable, ‘upon Me whom they have pierced’ (Zech.12.10). Here is both the unique and the firstborn Son, wounded by His own household. Might then His death be linked to a new birth?

In Colossians 1.15, Christ is declared the firstborn of all creation, not as the New World Translation heretically interpolates because ‘by Him all other things were created’ (v.16). The firstborn denotes not His title as Creator, but His acquired right as Joseph’s antitype, the One who humbly set aside reputation to take a servant’s place, and in vindication of His merit receives the inheritance of all things. How was this inheritance obtained? He ‘became obedient unto death, even the death of the cross. Wherefore God has highly exalted him, and given him a name which is above very name.’ (Phil.2.8-9). Colossians also underscores this, He is the firstborn from the dead (1.18) – His grave became the womb of His second birth to an unending life. To this also John alludes, He is ‘the first begotten from the dead’ (Rev.1.5), binding it to His priestly work of loving us and washing us by blood (v.5) and to the derivative priesthood into which we enter to His glory (v.6). The ‘Church of the firstborn’ is likewise gathered by His priestly mediation of a new covenant in sprinkled blood (Heb.12.24). Thus he becomes the true Passover, our firstborn substitute, by Whose blood we are spared the destroyer (Heb.11.28), a surety as Judah was to be for Benjamin (Gen.43.9, 44.32).

Here is the sense of that profoundly mysterious decree that echoes the eternal begetting of the Son, but this begetting, not merely its declaration, is curiously limited to a specific day, ‘Thou art my Son; this day have I begotten Thee’ (Ps.2.7). He is the Son, yet is begotten. This royal decree opens the gate to the Messiah’s inheritance of the nations and of the uttermost parts of the earth. So it is that Paul expounds this promise in Acts 13.33, ‘in that he hath raised up Jesus again’. Again, it is to this entitlement of an all encompassing inheritance, after taking seat at the right hand, that the same psalm is referred in Hebrews 1.4-5. In the next verse (v.6) allusion is made to Psalm 97.7, a jewel set amongst collected psalms of advent and judgement, when all the gods of this world must worship this humbled and exalted Son of God, Son of man, and Son of the resurrection – here is the Firstborn. In this decree, the Father founds Christ’s kingly office upon the vindication and perfection of His priesthood, for only so He is lawfully the King of Righteousness (Melchizedek), here is the proper sense of Heb.5.5. Noble John Owen properly objects to Socinian violence to Christ’s priesthood by delaying its completion till after Christ’s death, yet not the consecration of Christ to the priesthood but the perfection of His completed work is here in view (Heb.5.9). This foreordained decree was doubtless part of joy for which He endured the cross (12.2). John Flavel aptly writes of Psalm 2.7, ‘It is spoken of the day of his resurrection, when he had finished his sufferings; and so the apostle expounds and applies it, Acts 13: 32,33; for then did the Lord wipe away from the reproach of his cross. As if the Father had said, “Now thou hast again recovered thy glory, and this day is to thee as a new birthday.”’

In suffering then He became the firstfruits from the grave, and Christ has removed its victory over us. By condescending to be the first Child of the resurrection, He has brought His blood-bought also into the same family (Lk.20.35-6, Isa.8.18). Here is the reason for His triumphant report of adoption to Mary in the garden, ‘I ascend unto my Father, and your Father; and to my God, and your God.’ (Jn.20.17). This is the source of His seed and generation (Ps.22.30-21), a people begotten by His work. This is the root of the new creation every believer in Christ experiences, by death and resurrection in Him, who ‘died for them and rose again’ (2 Cor.5.14-15,17).

Here too is the key to the dual sense of the Greek term diayhkh in Heb. 9.16-17 for two quite distinct legal arrangements, a covenant and a testament. Christ the Testator Who died has become the firstborn heir. His effective mediation of this covenant by death has transformed it into a testament, v.15, a testament of a glorious inheritance (just as Jonathan’s also was to Mephibosheth (1 Sam.20.15-6, 2 Sam.9.7)), but this Testator yet lives! By this testament, we are graciously constituted coheirs, by being begotten into the sonship of holiness, by resurrection in His resurrection, after death to sin in His death (Rom.6.4, 1 Pet.1.3, Gal.4.2-7), being conformed to the image of the Firstborn Son (Rom. 8.29). By all this, Christ has become the eternal Father of His people, the King of His inheritance, and we His firstfruits, to the glory of His Father: that God might be all in all, the One to Whom all is subject and the One Who renders up all (Isa.9.6, Ps.33.12, 1 Cor.15.28).

O that those specifically responsible for the piercing of the Son might, as our text prophesies,  themselves see and relish the fruits of that ‘blood of sprinkling which speaketh better things than that of Abel’, and recover the inheritance of their fathers!

Footnotes
1 The principle Greek philosophical root of the sterile and cruel blasphemy of the Tauhid - which owes much more to Xenophanes and his heirs' crippling overreaction to the pagan anthropomorphisms of Hesiod and Homer than to the the Divine Spirit of Inspiration.

2 To those who argue that the Aramaic word 'Bar' (Heb. בר) could not be translated 'son' in the days of the United Kingdom, perhaps they should consult Proverbs. 31.2, where Solomon uses the same word three times for son. See also here for other Jewish translations which run the same way.

3 Capitalisation added.