Deu 6:4-5 “Hear, O Israel: The LORD our God, the LORD is one. You shall love the LORD your God with all your heart and with all your soul and with all your might.
The LORD our God, the LORD is one: This is the essential truth about God. He is a person and not a vague pantheistic force. Being one, He cannot be represented by contradictory images. Since the LORD our God is one, He is not Baal, or Ashtoreth – He is the LORD God, and they are not.
i. In the mind of many Jewish people, this verse alone disqualified the New Testament teaching that Jesus is God, and the New Testament teaching of the Trinity – that there is one God, existing in three Persons. At some times and places, as Jewish synagogues said the Shema together, and when the word one (echad) was said, they loudly and strongly repeated that one word for several minutes, as if it were a rebuke to Christians who believed in the Trinity.
ii. Christians must come to a renewed understanding of the unity of God. They must appreciate the fact that the LORD is one, not three, as 1 Corinthians 8:6 says: yet for us there is one God. We worship one God, existing in three persons, not three separate gods.
iii. Yet, the statement the LORD is one certainly does not contradict the truth of the Trinity. In fact, it establishes that truth. The Hebrew word for one is echad, which speaks most literally of a compound unity, instead of using the Hebrew word yacheed, which speaks of an absolute unity or singularity (Genesis 22:2 and Psalm 25:16).
iv. The very first use of echad in the Bible is in Genesis 1:5: So the evening and the morning were the first day. Even here, we see a unity (one day) with the idea of plurality (made up of evening and morning).
· Genesis 2:24 uses echad in saying the two shall become one flesh. Again, the idea of a unity (one flesh), making a plurality (the two).
· In Exodus 26:6 and 11, the fifty gold clasps are used to hold the curtains together, so the tent would be one (echad) – a unity (one) made up of a plurality (the many parts of the tabernacle).
· In Ezekiel 37:17 the LORD tells Ezekiel to join together two sticks (prophetically representing Ephraim and Judah) into one (echad), speaking again of a unity (one stick) made up of a plurality (the two sticks).
v. There is no way that echad has the exclusive idea of an absolute singularity; the idea of One God in Three Persons fits just fine with the term echad. (Guzik)