These two verses form a chiasm in the Hebrew. A chiasm is simply a structure that the Psalmist used to highlight something important. In a chiasm the central idea is always found in the middle. In our verse, the chiasm is this:
(a1) What I am afraid
(b1) I put my trust in you
(c) In God, whose word I praise (or I praise God for what He has promised)
(a2) I trust in God
(b2) So why should I be afraid
What can mere mortals do to me?
You can see how David moves from a point of fear to the point of trusting God, not being afraid, and then exclaiming how mere mortals cannot do anything to him. In the center of it all is the reason for his trust and confidence: God’s word. God’s word is trustworthy and when God says something that is the way it is.
God created the world simply by speaking it into being – it is in that powerful word that we put our trust. When David was feeling afraid and was being pursued by his enemies (as he was in this passage), he took comfort and found courage in the Word. John tells us that the Word is Jesus (John 1).
When our fears start to take hold of us, we simply need to remember that Jesus had the power to simply speak the world into existence, so certainly he has the power to be there in our time of need! When you’re feeling afraid, go to the Word of God and find comfort in the words given to us all – the very words of God.