Psalm 139

You know when I leave and when I get back; 
      I'm never out of your sight. 
   You know everything I'm going to say 
      before I start the first sentence. 
   I look behind me and you're there, 
      then up ahead and you're there, too— 
      your reassuring presence, coming and going. 
   This is too much, too wonderful— 
      I can't take it all in! 

 ^7-12 Is there anyplace I can go to avoid your Spirit? 
      to be out of your sight? 
   If I climb to the sky, you're there! 
      If I go underground, you're there! 
   If I flew on morning's wings 
      to the far western horizon, 
   You'd find me in a minute— 
      you're already there waiting! 
   Then I said to myself, "Oh, he even sees me in the dark! 
      At night I'm immersed in the light!" 
   It's a fact: darkness isn't dark to you; 
      night and day, darkness and light, they're all the same to you. 

David is having a moment of revelation regarding the scope of God's reach.  God is everywhere, there is no place we can be that He is not there with us.  For the child of God that is so comforting.  David marveled at this in Psalm 23 as well, "even though I walk through the valley of the shadow of death you are with me, your rod and staff they comfort me."  God speaking to Joshua told him, "Be strong and courageous. Do not be afraid; do not be discouraged, for the Lord your God will be with you wherever you go.”

There is no situation, circumstance, place or time we can find ourselves in where God is not with us.  He is with us, He loves us and will keep us.  We must come to a place of believing that and living it out.  He is with us, there is no need to be afraid.