Deut 6:4

6:4 Hear, O Israel. Often called the Shema, from the initial Hebrew word meaning “Hear,” this verse became the great confession of Israel’s monotheistic faith, and is recited morning and evening by Jews (cf. Mark 12:29). See note 5:1.

The Lord . . . Lord is one. Though the Hebrew may be translated several ways (text note), it is best to understand the verse as affirming both God’s uniqueness and unity or singularity—the only God is “one” (Mark 12:29). As the Old Testament implies and the New Testament explicitly teaches, however, there is differentiation of Persons within the unity of the Godhead. See “One and Three: The Trinity” at Is. 44:6.