"Think for a moment how many different sinful actions and attitudes come from anxiety. Anxiety about finances can give rise to coveting and greed and hoarding and stealing. Anxiety about succeeding at some task can make you irritable and abrupt and surly. Anxiety about relationships can make you withdrawn and indifferent and uncaring about other people. Anxiety about how someone will respond to you can make you cover over the truth and lie about things. So if anxiety could be conquered, a mortal blow would be struck to many other sins." (John Piper)
. . . One of the most important texts has been one I underlined when I was 15 — the whole section of Matthew 6:25–34. Four times in this passage Jesus says that his disciples should not be anxious.
Verse 25: "For this reason I say to you, do not be anxious for your life."
Verse 27: "And which of you by being anxious can add a single cubit to his life's span?"
Verse 31: "Do not be anxious, saying, 'What shall we eat?'"
Verse 34: "Therefore do not be anxious for tomorrow."
Anxiety is clearly the theme of this text. It makes the root of anxiety explicit in verse 30: "But if God so arrays the grass of the field, which is alive today and tomorrow is thrown into the furnace, will he not much more do so for you, O men of little faith?" In other words, Jesus says that the root of anxiety is inadequate faith in our Father's future grace. As unbelief gets the upper hand in our hearts, one of the effects is anxiety. The root cause of anxiety is a failure to trust all that God has promised to be for us in Jesus.