Worry is a form of pride because when believers are filled with anxiety, they are convinced that they must solve all the problems in their lives in their own strength. The only god they trust in is themselves. When believers throw their worries upon God, they express their trust in his mighty hand, acknowledging that he is Lord and Sovereign over all of life.
Thomas Schreiner, 1, 2 Peter, Jude, (B & H, 2003), pgs 240–241
