Does the Old Testament have evidence of the triune God?
Yes. The Old Testament contains evidences of the triune God, though it is vague about the Trinity. The Hebrews and rabbis, even today, do not recognize the Trinity in the Old Testament and accuse Christians of worshiping three gods. The fuller revelation is that God is Father, Son, and Holy Spirit.
Les explains that the Old Testament is vague about the Trinity, yet it has evidences of the triune God. This is why the Hebrews and rabbis, even in the present day, call Christians almost pagan, because they think Christians worship three gods; they do not recognize the Trinity in the Old Testament. Les teaches that the triune God—Father, Son, and Holy Spirit—is a revelation Paul brings out as part of the mystery.