Muslims argue that the concept of the Trinity is not present in the Old Testament and that Isaiah does not support the idea of a triune God.

In Isaiah 48:16, the text presents a speaker who claims to be sent by the Sovereign Lord and His Spirit, which many commentators identify as the Servant of the Lord, or the Messiah. This interpretation is significant because it highlights a divine figure who is distinct yet closely associated with Yahweh, suggesting a multi-faceted understanding of God that aligns with Trinitarian theology. Furthermore, the Servant's role as the one who speaks on behalf of God and is empowered by His Spirit indicates a relationship that transcends mere human understanding of singularity. Moreover, the context of Isaiah's prophecies, including the subsequent chapters, reinforces the idea that the Servant is central to God's redemptive plan. In Isaiah 49:1-3, the Servant is called from the womb and designated to bring glory to God, further emphasizing the unique identity and mission of this figure. This understanding of the Servant as both distinct from and unified with God supports the Christian doctrine of the Trinity, where Jesus, as the Messiah, embodies both divine and human natures. Lastly, the interpretation of Isaiah 48:16 as a Trinitarian reference is not merely speculative but is supported by the broader narrative of Scripture, where the roles of the Father, Son, and Holy Spirit are intricately woven throughout the biblical text. Thus, while Muslims may assert that the Trinity is absent in the Old Testament, a careful examination of Isaiah reveals a deeper theological richness that aligns with Christian beliefs about the nature of God.