This word comes from “omni” meaning “all” and “science” meaning “knowledge.” God knows all true propositions—whether past, present, or future. Consider several passages on the subject of omniscience:
(Ps. 139:1-6) O Lord, You have searched me and known me. 2 You know when I sit down and when I rise up; You understand my thought from afar. 3 You scrutinize my path and my lying down, and are intimately acquainted with all my ways. 4 Even before there is a word on my tongue, behold, O LORD, You know it all. 5 You have enclosed me behind and before, and laid Your hand upon me. 6 Such knowledge is too wonderful for me; it is too high, I cannot attain to it.
(Job 28:24) He looks to the ends of the earth and sees everything under the heavens.
(Job 31:4) Does He not see my ways and number all my steps?
(Prov. 15:3) The eyes of the LORD are in every place, watching the evil and the good.
(Mt. 10:29-30) Are not two sparrows sold for a cent? And yet not one of them will fall to the ground apart from your Father. 30 But the very hairs of your head are all numbered.
(1 Chron. 28:9) As for you, my son Solomon, know the God of your father, and serve Him with a whole heart and a willing mind; for the LORD searches all hearts, and understands every intent of the thoughts.
(Ps. 44:21) Would not God find this out? For He knows the secrets of the heart.
(Jer. 17:9-10) The heart is more deceitful than all else and is desperately sick; who can understand it? 10 I, the LORD, search the heart, I test the mind, even to give to each man according to his ways, According to the results of his deeds.
(Heb. 4:13) And there is no creature hidden from His sight, but all things are open and laid bare to the eyes of Him with whom we have to do.
(1 Jn. 3:20) God is greater than our heart and knows all things.
(Ps. 139:4; 14b-16) Even before there is a word on my tongue, Behold, O LORD, You know it all… Wonderful are Your works, and my soul knows it very well. 15 My frame was not hidden from You, When I was made in secret, and skillfully wrought in the depths of the earth; 16 Your eyes have seen my unformed substance; and in Your book were all written the days that were ordained for me, when as yet there was not one of them.
(Isa. 46:10) Declaring the end from the beginning, and from ancient times things which have not been done, saying, ‘My purpose will be established, and I will accomplish all My good pleasure.’
(Rom. 11:33-34) Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and unfathomable His ways! 34 For who has known the mind of the Lord, or who became His counselor?
(Job 21:22) “Can anyone teach God knowledge, in that He judges those on high?
(Ps. 147:5) Great is our Lord and abundant in strength; His understanding is infinite.
(Isa. 40:28) [God] does not become weary or tired His understanding is inscrutable.
Doesn’t God’s omniscience eliminate his own freewill? If God knows what He is going to do, then how can He choose to act differently?
Atheist Richard Dawkins argues, “If God is omniscient, he must already know how he is going to intervene to change the course of history using his omnipotence. But that means he can’t change his mind about his intervention.” Does God’s omniscience preclude his freedom to make decisions?
God’s foreknowledge does not determine his future actions. Instead, his future actions determine his foreknowledge. Therefore, God’s future actions are logically prior to his foreknowledge—even though they are historically after his knowledge of them. God cannot perform actions that contradict his foreknowledge, only because his foreknowledge perfectly reflects what he will freely do.
In the same way, God can’t perform actions that contradict his moral nature. Does this mean that his moral nature controls his actions? Yes, but remember, this is His nature. He is being “controlled” by himself!
What about open theism?
See our earlier article “A Critique of Open Theism.”
When we adopt a robust view of God’s omniscience, a number of practical implications closely follow:
We should confess sin that is hidden. Consider Adam’s folly in the Garden. He thought he could hide in the bushes from an omniscient God. We often think: what a fool! And yet, we do the same thing. When we fall into sin, we think that we can hide it from God or his people. David writes, “When I kept silent about my sin, my body wasted away through my groaning all day long. 4 For day and night Your hand was heavy upon me; My vitality was drained away as with the fever heat of summer. 5I acknowledged my sin to You, and my iniquity I did not hide; I said, ‘I will confess my transgressions to the LORD’; and You forgave the guilt of my sin. 6 Therefore, let everyone who is godly pray to You in a time when You may be found” (Ps. 32:3-6).
God is authorized to govern our lives. God knows what we need better than we do. Because we are both finite and fallen, we need to cultivate the habit of looking outside ourselves to God—especially to his word—for direction, rather than trusting our own inward thoughts and feelings. We cannot improve on God’s will for our lives (Rom. 12:1-2; Eph. 2:10). He not only knows, but he knows best (Prov. 3:5-6).
God’s love is greater than we could imagine. God’s omniscience is a source of security in God’s love. There are no skeletons in our closet. God knows about our sin more than any other person, but he loves us more than any other person. This multiplies the grace of God exponentially. He sees all the way into our heart (1 Sam. 16:7; Ps. 103:14), which is deceitfully wicked (Jer. 17:9). Yet he still loves us (1 Cor. 13:12; Gal. 4:9; 1 Cor. 8:3; 1 Jn. 3:20).
 Dawkins, Richard. The God Delusion. Boston: Houghton Mifflin, 2006. 78.