“know” = ginosko =  to learn to know, come to know, this indicates knowledge that is acquired. The second “know” in “I know him.” = eido =  to see  to perceive with the eyes; to know. This indicates that which is grasped intuitively, by direct personal cognition. (TFG) The Jews had not acquired a knowledge of God from their Scriptures.

God is not really their God at all; if He had been, then they would have known Him, but as it was, all they knew were facts about Him. They had no personal relationship with God.

“keep his word” = to act in accordance with everything God has revealed about Himself. Why does Jesus tie this together with knowing God?

Barclay points out that Jesus has claimed unique knowledge of God and unique obedience to Him. This proves that “the only way to full knowledge of the heart and mind of God is through Jesus Christ” and that “to look at Jesus is to be able to say: ‘This is how God wants me to live.’”