Even though the Trinity is a mystery, it can be defined very simply: “There is one God who exists eternally in three persons.” While this paradox is hard to comprehend, we believe it because it is the only view of God that is faithful to everything God has revealed about himself in the Bible. That revelation starts with the oneness of God.
The Trinity starts with the concept, deeply rooted in the Jewish Scriptures, that there is only one God.
Christianity was birthed out of Judaism, which is strongly monotheistic, based on the testimony of the Old Testament scriptures. Every day faithful Jews recited, “The Lord is our God, the Lord is one.” (Deuteronomy 6:4). This is the conviction Jesus’ disciples inherited and which they expressed in the New Testament. While people worship many different gods, only one God is real. Only one God created all things (1 Corinthians 8:5-6). As the first Christians wrestled with the identity of Jesus, they never wavered from the clear understanding that there is only one God (1 Timothy 2:5; Romans 3:30).
At some point in Christian history, each key part of the classic definition of the Trinity has been challenged. One challenge claims that the Father, Son and Holy Spirit are separate, distinct beings. Each has his own independent existence. This error takes the “three persons” part of the Trinity seriously, but it falls short on the “one God” side of the equation. This is a heresy called Tritheism.
“Tri-theism” is a heresy that misses the oneness of God, teaching that there are three distinct gods who work closely together.
This view is very rare in Christian history, because the teaching of monotheism in the Bible is so clear. But one contemporary expression is Mormonism. They teach that Father, Son and Holy Spirit form one “godhead”, but not one God. The members of the godhead are one in purpose or will, but not in essence.
But in the Bible, God states, “I alone am God! I am God, and there is none like me” (Isaiah 46:9) and “You are my witnesses – is there any other God? No!” (Isaiah 44:8). This is an absolute statement. There are not three (or more) beings who can be called “God”.
So what does it matter that God is one? How does this theological truth impact our daily lives? The answer is that the existence of one God gives us peace and certainty in a world that can often seem transitory and confusing.
The existence of only one God helps us make sense of humanity, morality, and eternity.
If there is only one God, then there is only one Creator of the entire human race. In the ancient world, each nation had its own deities. Nations claimed supremacy over other nations based on the supposed supremacy of their gods. But if there is just one God who made all people, then all humanity is one (Acts 17:26). We should not separate into competing tribes or claim superiority over other peoples.
If there is only one God, then there is only one Lord who has the authority to establish a universal moral code (Psalm 96:13). Since only one God rules the universe, every human being is answerable to him, and we will all be judged by the same standard.
If there is only one God, then there is only one Savior and one way to salvation. In the Bible, God says, “I alone am God. There is no other God – there never has been, and there never will be. I, yes I, am the Lord, and there is no other Savior” (Isaiah 43:11). There aren’t several pathways to eternal life, just one – because God is one.
The Bible undeniably teaches the oneness of God. That’s the starting point for the doctrine of the Trinity.
