"Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and minds in Christ Jesus” (Philippians 4.6-7 ESV).
Our minds are wonderful creations of God. But did you know they need to be guarded? When I was a boy I used to play with Silly Putty. You could do a lot of neat things with it. You could make shapes, and you could even bounce it like a ball. But the best thing to do was to flatten it out, press it on the Sunday comics, and pull up a copy of the comic on the Silly Putty. Our minds are like that too! They are made by God to pick up everything. If we constantly expose our minds to bad things, they will get filled with bad thoughts and desires. Prayer points our minds toward God, cleanses our hearts and minds, and fills them with good things. All of this helps to control anxiety.
For more on the problems of anxiety and the help that God gives us see my sermon "The Right Things Really Matter." (October 10, 2011)
