1.8 Could there be only one truth?
Truth is something that is objectively true and therefore doesn’t depend on what people think about it. Jesus said that he himself was the truth Jn. 14:6: Jesus said to him, “I am the way, and the truth, and the life; no one comes to the Father, but by me.”.
The truth that Jesus teaches us and embodies is objectively true and therefore doesn’t depend on the number of people who believe in him. Jesus teaches us that God created us, that he loves us very much, and that he hopes that we will say “Yes” to his invitation to be happy with him in heaven.
The Wisdom of the Church
In that way is God the truth?
God is truth itself and as such he can neither deceive nor be deceived. He is “light, and in him there is no darkness” (1 John 1:5). The eternal Son of God, the incarnation of wisdom was sent into the world “to bear witness to the Truth” (John 18:37). [CCCC 41]
What does it mean to say that God is truth?
“God is light and in him is no darkness” (1 Jn 1:5). His Word is truth (Prov 8:7; 2 Sam 7:28), and his Law is truth (Ps 119:142). Jesus himself vouches for God’s truth by declaring before Pilate, “For this I was born, and for this I have come into the world, to bear witness to the truth” (Jn 18:37).
The truth of God cannot be “proved” or subjected to empirical tests, since science cannot make him an object of investigation. And yet God subjects himself to a special sort of proof. We know that God is truth on the basis of the absolute credibility of Jesus. He is “the way, and the truth, and the life” (Jn 14:6). Anyone who enters into a relationship with him can find this out by putting it to the test. If God were not “true”, then faith and reason could not have a dialogue with each other. An agreement is possible, however, because God is truth, and the truth is divine. [Youcat 32]
This is what the Church Fathers say
True religion consists in the service of the one true God. That God is one, is truth itself. And just as without that one truth there is no other truth, so also without the one true God there is no other true God. For that one truth is one divinity. And so we cannot say truly that there are two true gods, just as truth itself cannot naturally be divided. [St. Fulgentius, Eighth letter (ML 56, 365)]