Old school exegetical arguments for the deity of Christ start from the Pentateuch. The following is from Justin Martyr's (c. 100-165 AD) work Dialogue with Trypho:
When I had spoken these words, I continued: “Permit me, further, to show you from the book of Exodus how this same One, who is both Angel, and God, and Lord, and man, and who appeared in human form to Abraham and Isaac, appeared in a flame of fire from the bush, and conversed with Moses.”
And after they said they would listen cheerfully, patiently, and eagerly, I went on: “These words are in the book which bears the title of Exodus: ‘And after many days the king of Egypt died, and the children of Israel groaned by reason of the works;’ and so on until, ‘Go and gather the elders of Israel, and thou shalt say unto them, The Lord God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath appeared to me, saying, I am surely beholding you, and the things which have befallen you in Egypt.’ ”
In addition to these words, I went on: “Have you perceived, sirs, that this very God whom Moses speaks of as an Angel that talked to him in the flame of fire, declares to Moses that He is the God of Abraham, of Isaac, and of Jacob?"