The conclusion to my dad's outstanding essay (the deity of Christ in the OT) contains rich biblical-theological wisdom, profitably reflected on slowly--
'And the Scripture, forseeing . . .' (Gal. 3:8). There is a forward tilt built into the Bible. It is not imposed by the dogmatist. It is embedded within. As the story moves forward from the 'unfinished symphony' of the Old Testament to the denouement of the New, its truths intensify in clarity. There is no reason why that progress of thought should not include the deity of the Christ. Not all Christian exegesis of the relevant texts is convincing in all respects, and doubtless some of my proposals here have failed to satisfy some readers. Still, 'the Scripture, foreseeing' requires the faithful interpreter to allow for the clearer light of the New Testament to dawn in the Old. I believe that is warranted in the case of the divine Christ.--Raymond C. Ortlund Jr, 'The Deity of Christ in the Old Testament' in The Deity of Christ (ed. Robert Peterson and Christopher Morgan; Crossway, 2011), 58-59
Disciplined by cautious exegesis—indeed, compelled because of that caution—I must conclude that the deity of the Christ is unmistakably, if mysteriously, revealed in Old Testament texts. The key passages raise questions more than they answer questions. But that is a valid function of the Old Testament, for incomplete revelation is still revelation and a fitting preparation for the full Christ of the New Testament. Psalm 45 rejoices in One who is both royal groom and eternal Ruler. Psalm 110 esteems the son of David who also towers over David as God’s final answer to worldwide human rebellion. Isaiah 9 celebrates the birth of a child who, as our divine Warrior and endless Benefactor, will advance David’s kingdom successfully and infinitely. Daniel 7 reveals heaven's decree of worldwide, eternal authority conferred on a celestial Being who stands forth also as a man. These passages cannot convincingly be made to say less, and their assertions are consistent with the later faith of the Christian Church.
To quote Canon Liddon, 'Do we not already seem to catch the accents of those weighty formulae by which Apostles will presently define the pre-existent glory of their Majestic Lord?' But divorce the text of the Old Testament from the hope of a divine Messiah—'how full of difficulties does such language forthwith become, how overstrained and exaggerated, how insipid and disappointing!'