How do we know God's omniscience is true?

The truth of God's omniscience is grounded in Scripture, where it is revealed that He knows every thought, word, and deed. Psalms highlight this knowledge, as seen in Psalm 139:1-4, where David proclaims that God knows us fully, even before we speak. Furthermore, understanding that God's knowledge is tied to His sovereign will reinforces the certainty of this attribute; He does not merely know what will happen but ordains it. As such, believers can rest in the assurance that nothing escapes His sight or understanding.