What Does it Mean that God is Omniscient?

Omniscience is an attribute of God alone. It is the quality of having all knowledge (Is. 40:14). Omnipotence, omnipresence, and omniscience represent the nature of God concerning His relation to the creation.

GodisOmniscient533x400   GOD KNOWS EVERYTHING AND HE SEES EVERYTHING

God sees and knows all things.  In the Old Testament omniscience is expressed in connection with such words as "seeing" and "hearing," "the eye" and "the ear" occur as figures for the knowledge of God, as "arm," "hand," "finger" serve to express His power. In the New Testament are found ginoskein, gnosis, eidenai, and sophia, in the same connections.

God sees all things (Proverbs 15:3) .

He knows the size and scope of the universe (Psalm 147:4).

Jesus said that God the Father knows about the animal creation (Matthew 10:29)

Our Father knows mankind, Jesus said (Matthew 10:30).

He knows our thoughts (Psa. 139:2b; 44:21), words (Ps. 139:4), and deeds (Psa. 139:2a).

God knows our sorrows (Exodus 3:7).

He knows our devotions (Genesis 18:17-19; 22:11-12; 2 Chronicles 16:9—whose hearts are perfect towards Him).

He knows our frailties (Ps. 103:14).

God knows our folly (Ps. 69:5).

He knows His own (John 10:14; 2 Tim. 2:19).

As hinted at above, God knows the past, present, and future (Acts 15:18).

He knows the actual as well as the possible; He knows what might or could have been (Matt. 11:23).

To condense things a bit, key verses relating to the doctrine of omniscience are:

Psalm 147:4–5

⁴      He telleth the number of the stars;

He calleth them all by their names.

⁵      Great is our Lord, and of great power:

^pHis understanding is infinite.

Proverbs 15:3

³      The eyes of the Lord are in every place,

Beholding the evil and the good.

Isaiah 29:15

¹⁵    Woe unto them that seek deep to hide their counsel from the Lord,

And their works are in the dark,

And they say, Who seeth us? and who knoweth us?

Matthew 10:28–30

²⁸ And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell. ²⁹ Are not two sparrows sold for a farthing? and one of them shall not fall on the ground without your Father. ³⁰ But the very hairs of your head are all numbered.

Hebrews 4:13

¹³ Neither is there any creature that is not manifest in his sight: but all things are naked and opened unto the eyes of him with whom we have to do.

See also Pr.15:3