1. "O LORD, thou hast searched me, and known me.
2. Thou knowest my downsitting and mine uprising, thou understandest my thought afar off."
God alone is omniscient. He has complete and unlimited knowledge about everything and everyone. God’s omniscience is one of His attributes that He does not share with us. God's knowledge of each person is as such that nothing, absolutely nothing, is hidden from Him.
Isaiah 46: 9-10 gives us a clear picture of God's omniscience. The verses state,
"Remember the former things of old: for I am God, and there is none else; I am God, and there is none like me,
Declaring the end from the beginning, and from ancient times the things that are not yet done, saying, My counsel shall stand, and I will do all my pleasure:"
We must be ever aware that God knows us better than we know ourselves or than anyone else does. He created us, therefore, He knows every part of our inner being. I am sure that we have said at one time or another, "I can't believe that I did that." or "I can't believe that I said that." Sometimes, based on our words and our actions, we can surprise ourselves. God is never surprised by what we think, say or do.
Verse 2 of Psa 139 reminds us that God knows when we sit down and when we get up. God knows us personally and intimately, and He has a special, unique plan for each one. It is comforting to know that everything, which happens in our lives, is known to God before it occurs.
We cannot fully understand how God is working in our lives, but we can trust Him explicitly, unreservedly to work His purposes out for our advantage. Success is guaranteed when we stay with God.