Why does God know every thought and everything we do?
Because the Holy Spirit indwells every believer from the moment of faith, making the body the temple of God. The third person of the Trinity comes to dwell within, so God's presence is not distant; He is here, knowing every thought, place, and deed.
Les explains that every believer, the moment he believes, is indwelt by the Spirit. The body becomes the temple of the indwelling Holy Spirit, and you cannot check God at the door or leave Him behind. That is why God can know every thought, every place we go, and everything we do: because He is here. Les illustrates this with Solomon's temple, where the Shekinah glory came down and the presence of God dwelt in that dwelling place. That was a foreview of this age of grace, when God saves an individual and immediately makes that person a temple, a dwelling place; just as the Shekinah glory came into Solomon's temple, the Holy Spirit comes into us.