In order to know and understand truth we must go to the correct source. God is declared to be the God of truth in Deuteronomy 32:4 and Psalm 31:5.
He is the Rock, His work is perfect; For all His ways are justice, A God of truth and without injustice; Righteous and upright is He;…Deuteronomy 32:4
Into Your hand I commit my spirit; You have redeemed me, O Lord God of truth. Psalm 31:5
Jesus Christ declared Himself to be the truth in John chapter 14.
Jesus said to him, “I am the way, the truth, and the life. No one comes to the Father except through Me.” John 14:6
Jesus Christ also said He came to bear witness to the truth in John chapter 18.
Pilate therefore said to Him, “Are You a king then?” Jesus answered, “You say rightly that I am a king. For this cause I was born, and for this cause I have come into the world, that I should bear witness to the truth. Everyone who is of the truth hears My voice.” John 18:37
If we want to know the truth we must go to the source of truth, the One Who is the truth, Jesus Christ.
When Jesus Christ declared that He came into the world to bear witness to the truth He was indicating that there is a permanent repository of the truth. He lets us know what it is in His prayer to the Father in John chapter 17.
“Sanctify them by Your truth. Your word is truth.” John 17:17
He also promised to send One Who guides us into all truth, the Holy Spirit.
…”but when the Helper comes, whom I shall send to you from the Father, the Spirit of truth who proceeds from the Father, He will testify of Me.” John 15:26
13 “However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. 14 “He will glorify Me, for He will take of what is Mine and declare it to you.” John 16:13 & 14:
We come to know and understand the truth by believing in the One Who is the truth, that is Jesus Christ the Son of God; by trusting and believing in His written word, the Bible; and then relying on the Holy Spirit to teach us the truth from the Bible, the Word of God. There is no other source of truth that God has given to us to enlighten us and set us free. This is what Jesus said to those Jews who believed Him:
“If you abide in My word, you are My disciples indeed. “And you shall know the truth and the truth shall make you free.” John 8:31