Jesus, being the Only Begotten Son of God, shares His Divine Nature. He is love in Person. He said He is the Son of God, that is the reason the Jews crucified Him. As we read in the Gospel of Mark, “The High Priest put a second question to him, ‘Are you the Christ, the Son of the Blessed One?’ Then Jesus answered, ‘I am, and you will see the Son of Man seated at the right hand of the Most Powerful and coming with the clouds of heaven around him.’ The High Priest tore his clothes to show his horror and said, ‘What more evidence do we need? You have just heard his blasphemous words. What is your decision?’ And they all condemned Jesus saying, ‘He must die’” (Mk. 14:61-64).
Jesus proved it so because many witnessed His Resurrection and His many miracles that no man ever did before. He is true God and true man. That is why we say: “And the Word was made flesh; he had his tent pitched among us, and we have seen his Glory, the Glory of the only Son coming from the Father: fullness of truth and loving-kindness” (John 1:14). “Yes, God so loved the world that he gave his only Son that whoever believes in him may not be lost, but may have eternal life” (Jn. 3:16).