Another aspect of God’s nature that Christians in general agree on is that He is omniscient.  Omniscience means to have infinite awareness, understanding and insight, or to possess universal or complete knowledge.  Given that we believe He is omnipresent, the idea that God knows everything there is to know is a reasonable conclusion.  From this Evangelical site:

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).

https://www.gotquestions.org/God-omniscient.html

One of my favorite Scriptures that speaks to this truth is Hebrews 4:13 – “And before him no creature is hidden, but all are open and laid bare to the eyes of him with whom we have to do.”  And there are many others we can refer to in order to better understand this aspect of God’s nature:

Psalm 33:13-14 The LORD looks down from heaven, he sees all the sons of men; from where he sits enthroned he looks forth on all the inhabitants of the earth

1 Chronicles 28:9 And you, Solomon my son, know the God of your father, and serve him with a whole heart and with a willing mind; for the Lord searches all hearts, and understands every plan and thought.  If you seek him, he will be found by you; but if you forsake him, he will cast you off for ever.

Acts 1:24 And they prayed and said, “Lord, who knowest the hearts of all men, show which one of these two thou hast chosen”

Other verses to consider: Psalm 147:4-5, 1 Samuel 16:6-7, Isaiah 40:28, Isaiah 42:9, Jeremiah 29:11, John 21:17, Romans 11:33-34

Why is this topic that important?  This topic speaks to the perfection of God – His perfect understanding and insight compared to our limited view.  What if we view the story of the universe and our existence as a great novel God is writing out over time and space?  Can we then understand that our view of this masterpiece is limited to but a sentence or two in one paragraph?  Could perhaps our perspective be so limited we can’t fathom the depth of understanding that God has of our role in this story and our purpose?  And if we recognize this truth, can it lead us to more a perfect trust?  While we may not understand many things that happen in “our part” of this epic tale, we can truly know that “in everything God works for good with those who love him, who are called according to his purpose.” (Romans 8:28)  May we always remember that He is God, and we are not.