Muslims often argue that the concept of the Trinity is not supported by the Old Testament and that God is a singular entity without any partners or divisions.

The Old Testament consistently emphasizes the uniqueness and sovereignty of Yahweh, declaring that there is none like Him. However, within this framework, there are passages that suggest a multi-personal aspect of God's nature. For instance, Isaiah 48:16 presents a scenario where Yahweh speaks of being sent by Yahweh and His Spirit, indicating a plurality within the Godhead. This is a significant point for Christians who see it as an early indication of the Trinitarian concept. Furthermore, the prophetic writings often highlight the relationship between the Father, the Son, and the Holy Spirit, suggesting that while God is one, He exists in a complex unity. This is not in contradiction to the monotheistic belief but rather enriches the understanding of God's nature. The New Testament further clarifies this relationship, affirming that Jesus is the Son of God and part of the divine essence. In light of these scriptures, Christians argue that the Old Testament does not deny the Trinity but rather supports it through its portrayal of God's interactions and revelations. The complexity of God's nature is a mystery that transcends human understanding, yet it is foundational to the Christian faith.