Is God omniscient? What does it mean to be omniscient?

TL;DR:

God is omniscient, meaning He knows everything with absolute accuracy and perfect understanding. His knowledge is immediate, infinite, and completely unbound by time or human limitations.

To be omniscient means to possess all knowledge. God knows all facts, sees all events, understands all hearts, and perceives all motives. His knowledge is not learned or discovered—it is intrinsic to His nature. He never forgets, never guesses, and never learns something new. God knows every thought before it is formed, every word before it is spoken, and every deed before it is done. He sees into the deepest corners of the heart and mind. His knowledge encompasses what is, what was, what will be, and even what could have been. This knowledge is not cold or distant. God’s omniscience is always personal and purposeful. He knows His children intimately and works all things together for their good (Romans 8:28). Even the trials we do not understand are part of a plan known perfectly to Him.

from the old testament

The word omniscient comes from “omni” (all) and “scient” (knowledge), meaning God is all-knowing. Since God existed before creation and made everything, He knows all things because He is the Creator of all (Genesis 1:1).
However, omniscience is more than just general, external knowledge. The LORD told Samuel, “for God sees not as man sees, for man looks at the outward appearance, but the LORD looks at the heart” (1 Samuel 16:7). In the Bible, the “heart” doesn’t mean just emotion but includes our desires and thoughts. God knows who we are on the inside (Psalm 139:1-4). God even knows what we are going to say before we do.
Solomon prayed, “forgive and act and render to each according to all his ways, whose heart You know, for You alone know the hearts of all the sons of men” (1 Kings 8:39). Because God knows everything about everyone, He can perfectly execute justice.
Proverbs 15:11 observes, “Sheol and Abaddon lie open before the LORD—how much more the hearts of mankind!” The unseen world (“Sheol and Abaddon”) is plainly open before God, so every human motive is even clearer to Him.
God’s knowledge is not limited to what is happening now or what we are thinking now. God knows history before it happens because He creates everything, including history (Isaiah 46:9-10).

from the new testament

God’s omniscience is also affirmed in the New Testament. Hebrews 4:13 states, “no creature is hidden from his sight, but all are open and laid bare to him with whom we have to do.” Nothing escapes God's attention.
Jesus taught that God’s omniscience brings comfort. Even the fall of a tiny, seemingly insignificant sparrow does not escape the Father’s notice (Matthew 10:29-30). This shows that God is intimately aware of everything in creation.
God knows us to such a detail that He keeps track of even how many individual strands of hair we have (Matthew 10:31)!
Paul marveled, “Oh, the depth of the riches, both of the wisdom and knowledge of God!” (Romans 11:33-34). God's knowledge is beyond human comprehension. Scientists continue to discover ever smaller components that make up life and matter, yet God has always known and tracked these elements since He first created them. Similarly, His knowledge expands out into the universe to planets we haven’t yet discovered. We just cannot comprehend what it means to have so much knowledge at one time.
For the believer, God’s knowledge is particularly special. Paul says that “The Lord knows those who are His” (2 Timothy 2:19). Paul’s point is not merely that God knows about us but that He knows us in a relational way.
When God sent His Son, Jesus added on humanity. Paul taught, “although He existed in the form of God, did not regard equality with God a thing to be grasped, but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men” (Philippians 2:6-7). Jesus did not stop being God when He added on humanity. That means that Jesus, in His humanity, limited His knowledge (Matthew 24:36); in His divinity, He knows everything.
Jesus “knew all men, … for He Himself knew what was in man” (John 2:24-25). In His divinity, Jesus fully knows what each of us are thinking.

implications for today

God’s omniscience means that He knows everything we do or think. Because God knows everything, believers can take great comfort knowing that God knows about their trials and knows those causing the trials (Exodus 3:7). This means we can live faithfully, trusting Him to put everything right in the end.

However, it is also a frightening truth. For believers, it means that we can’t “coast” out our Christian life. God knows everything we do, for better or worse, and we will be judged in the end (2 Corinthians 5:10). We won’t lose our salvation, but we will suffer loss for all the sin we do. Additionally, God actively brings discipline to His sinning children to grow us to be more holy (Hebrews 12:6).

For the unbeliever, it means that God knows. What does he know? That memory of sin that just popped into your head—God knows that. He knows your thoughts even before you know them (Psalm 139:2-4) as well as every sin you ever committed. He has a record of them all (Revelation 20:12). You have two choices: You can continue to foolishly hope that judgement won’t come (Romans 1:18-23) or you can humble yourself and repent. Jesus promised that He will not cast out anyone who trusts in His righteousness for salvation (John 6:37), and the all-knowing Father has promised to forget the sins of the repentant (Hebrews 8:12).

In short, for both believer and unbeliever, God’s omniscience should cause us to worship and fear Him!

understand

God’s omniscience means He knows all things fully and perfectly.
God’s knowledge is both infinite and personal.
God’s omniscience is both comforting and convicting.

reflect

How does knowing that God sees every thought and motive in your heart challenge the way you live each day?
When you face trials or suffering, do you find comfort that God knows your situation completely? Why or why not?
Are there areas of your life where you act as if God doesn’t know or care? How might acknowledging His perfect knowledge change that?

engage

How can we help each other live in light of the truth that God knows everything we think, feel, and do?
How does God's omniscience offer both hope and accountability to believers today?
Why is it important to understand the difference between God knowing about us and God knowing us personally? How are we to reflect that aspect of God to others?