God is the main subject of Psalm 139, not David, not you, and not me.
*v.1-6 - God is omniscient.
The God who knows everything knows you: your actions, your heart/mind, your words, and your future.
*v.7-12 - God is omnipresent.
God’s presence has been, will be, and is now with His children. At all times and in all places, God is fully present.
*v.13-18 - God is omnipotent.
From even before conception – not just starting at birth – God is forming & knitting & writing our stories. God is completely sovereign over each one of us.
*v.19-24 - a right response to who God is.
When we see ourselves in comparison to the greatness of God, our hearts will be moved like David’s – to repentance and worship. Since God is not far from you, the proper response is to seek Him.