Christians claim that we have found it in Jesus, that Jesus is the Truth.
Jesus told him, “I am the way, the truth, and the life. No one can come to the Father except through me.” – John 14:6
When Jesus says He is the truth, He means He is the personification or the embodiment of truth.
He explains what it means to claim that He is the Truth – it means He is equal with God.
If you had really known me, you would know who my Father is. From now on, you do know him and have seen him!” – John 14:7
To know Jesus is to know the Father. Jesus claims that the disciples have seen God the Father.
It may well be that to the ancient world this was the most staggering thing Jesus ever said. To the Greeks God was characteristically The Invisible, the Jews would count it as an article of faith that no man had seen God at any time. To people who thought like that Jesus said: “If you had known me, you would have known my Father too.” Then Philip asked what he must have believed to be the impossible. Maybe he was thinking back to that tremendous day when God revealed his glory to Moses (Exodus 33:12-23). But even in that great day. God had said to Moses: “You shall see my back: but my face shall not be seen.” In the time of Jesus men were oppressed and fascinated by what is called the transcendence of God and by thought of the difference and the distance between God and man. They would never have dared to think that they could see God. Then Jesus says with utter simplicity: “He who has seen me has seen the Father.” – William Barclay
Absolute truth can be known because the Absolute has become concrete in history in the person of Jesus. Herein is the argument for our belief in absolute truth.