Question: "What does it mean that God is omniscient?"
Answer: Omniscience is defined as “the state of having total knowledge, the quality of knowing everything.” For God to be sovereign over His creation of all things, whether visible or invisible, He has to be all-knowing. His omniscience is not restricted to any one person in the Godhead—Father, Son, and Holy Spirit are all by nature omniscient.
God knows everything (1 John 3:20). He knows not only the minutest details of our lives but those of everything around us, for He mentions even knowing when a sparrow falls or when we lose a single hair (Matthew 10:29-30). Not only does God know everything that will occur until the end of history itself (Isaiah 46:9-10), but He also knows our very thoughts, even before we speak forth (Psalm 139:4). He knows our hearts from afar; He even saw us in the womb (Psalm 139:1-3, 15-16). Solomon expresses this truth perfectly when he says, “For you, you only, know the hearts of all the children of mankind” (1 Kings 8:39).
Despite the condescension of the Son of God to empty Himself and make Himself nothing (Philippians 2:7), His omniscience is clearly seen in the New Testament writings. The first prayer of the apostles in Acts 1:24, “Lord, you know everyone’s heart,” implies Jesus’ omniscience, which is necessary if He is to be able to receive petitions and intercede at God’s right hand. On earth, Jesus’ omniscience is just as clear. In many Gospel accounts, He knew the thoughts of his audience (Matthew 9:4; 12:25; Mark 2:6-8; Luke 6:8). He knew about people’s lives before He had even met them. When He met the woman collecting water at the well at Sychar, He said to her, “The fact is you have had five husbands, and the man you now have is not your husband” (John 4:18). He also tells His disciples that their friend Lazarus was dead, although He was over 25 miles away from Lazarus’s home (John 11:11-15). He advised the disciples to go and make preparation for the Lord’s Supper, describing the person they were to meet and follow (Mark 14:13-15). Perhaps best of all, He knew Nathanael before ever meeting him, for He knew his heart (John 1:47-48).
Clearly, we observe Jesus’ omniscience on earth, but this is where the paradox begins as well. Jesus asks questions, which imply the absence of knowledge, although the Lord asks questions more for the benefit of His audience than for Himself. However, there is another facet regarding His omniscience that comes from the limitations of the human nature which He, as Son of God, assumed. We read that as a man He “grew in wisdom and stature” (Luke 2:52) and that He learned “obedience through suffering” (Hebrews 5:8). We also read that He did not know when the world would be brought to an end (Matthew 24:34-36). We, therefore, have to ask, why would the Son not know this, if He knew everything else? Rather than regarding this as just a human limitation, we should regard it as a controlled lack of knowledge. This was a self-willed act of humility in order to share fully in our nature (Philippians 2:6-11; Hebrews 2:17) and to be the Second Adam.
Finally, there is nothing too hard for an omniscient God, and it is on the basis of our faith in such a God that we can rest secure in Him, knowing that He promises never to fail us as long as we continue in Him. He has known us from eternity, even before creation. God knew you and me, where we would appear in the course of time, and whom we would interact with. He even foresaw our sin in all its ugliness and depravity, yet, in love, He set his seal upon us and drew us to that love in Jesus Christ (Ephesians 1:3-6). We shall see Him face to face, but our knowledge of Him will never be complete. Our wonder, love and praise of Him shall go on for all millennia as we bask in the rays of His heavenly love, learning and appreciating more and more of our omniscient God.