Did believers in the Old Testament have a complete understanding of the Trinity?

Summary

The sermon discusses the presence of the Trinity in the Old Testament, acknowledging that while Old Testament Jews strongly emphasized God's oneness (referencing Deuteronomy 6:4-5), the Old Testament can be interpreted as containing foreshadowings of the Trinity that are more fully revealed in the New Testament. The key takeaway is that the Old Testament prepares the way for understanding the Trinity, though it was not explicitly articulated by Old Testament writers.