The phrase "This Is That" in Acts 2:16 is a reference to the prophet Joel's prophecy.
The foundation for understanding this verse is found in 2 Peter 1:20-21, where it is stated that no prophecy is of any private interpretation.
The second piece of the foundation is found in Isaiah 28:9-10, where it is stated that Jesus Christ is the same yesterday, and to day, and for ever.
This verse raises questions about the nature of Jesus' existence and role within the Godhead.
The Bible teaches that Jesus is fully God and fully human, with the Old Testament testifying that Jesus is God.
Isaiah prophesied that the Messiah would be called Immanuel, meaning God with us.
Jesus used this concept to confound the Pharisees when He quoted Psalm 110:1 and asked, "How could the Father not be God?".
The Bible's teachings on Jesus' identity and role within the Godhead have been a subject of debate among philosophers, teachers, and theologians.