How do we know God's testimony about Jesus is true?

The proof of God's testimony about Jesus being true lies in the historical fulfillment of prophecies and the nature of God's revelation throughout Scripture. God has consistently confirmed His word through the prophets, ultimately culminating in the person of Jesus Christ, whom He declared as His beloved Son. As seen in passages like Psalm 19 and the writings of the Apostle Paul, God's statements about Jesus are substantiated by the miracles, His resurrection, and the consistent nature of God’s character, which is faithful and true. Therefore, when we grasp this divine testimony, we can confidently trust that it is true.