1 John 5:11 ESV
And this is the testimony, that God gave us eternal life, and this life is in his Son.
The word of God is manifest in the Son. The testimony of Christ is that He brings eternal life and this life is in this Son.
This is the truth we must hold and remain steadfast in as we face a world that has little regard for truth.
Then I fell down at his feet to worship him, but he said to me, “You must not do that! I am a fellow servant with you and your brothers who hold to the testimony of Jesus. Worship God.” For the testimony of Jesus is the spirit of prophecy.