How God knows us, He is familiar with us. We are of great interest to God. This is difficult to comprehend. God must be love, grace and mercy. All who put their faith in Christ are his friends. To the most boring and mundane person, to the most active and exciting. It is no matter. The all-seeing, all-knowing God is familiar with all our ways. He being familiar, does not mean he just knows us, but he associates with us.
The word “acquainted” in the KJV and familiarity in the NAB are colder than the Hebrew teaches. God is associated with us by friendship. He makes it a habit of being around us, being seen with us, talking to us. He has decided to be our friend and He enjoys our company. Jesus is the friend of sinners and the friend of saints. He likes us as friends and loves us as children. I mean we all have people who love us but do not like us. It seems crazy but it is true. When people like us they like being around us and being with us.
This verse three of Psalm 139 says he “scrutinizes.” us. The word in Hebrew is sift or winnow. He inspects our travels and rest closely. It would seem he looks closely at our activity and leisure. He likes being a part of what we do. He lives in us and his word lives in us. It is no wonder that he is our friend.
When he scrutinizes it teaches that God isolates that which is most important or useful and gets rid of that which is undesirable. This can be a reference to growing in holiness as he purifies our heart, very true.
But it would also indicate that God is not pettily criticizing every word, action and thought. He KNOWS us. He sees the big stuff, the deep stuff, the stuff that counts in our lives and he loves that about us.
After all, we reflect who he is as he gives us holy desires and abilities.