Because of the presence of God, believers are to be anxious for nothing. Nothing is outside of His sovereign control or too difficult for Him to handle. A low view of God leads to a myriad of problems in the church:
The Church has surrendered her once lofty concept of God and has substituted for it one so low, so ignoble, as to be utterly unworthy of thinking, worshiping men. This she has done not deliberately, but little by little and without her knowledge; and her very unawareness only makes her situation all the more tragic.
The low view of God entertained almost universally among Christians is the cause of a hundred lesser evils everywhere among us. A whole new philosophy of the Christian life has resulted from this one basic error in our religious thinking. (Tozer, The Knowledge of the Holy, 6)
Weak, struggling, unstable Christians need to build their strength on the foundation of what the Bible says about God. The result of the church’s failure to equip believers with the knowledge of God’s character and works is a lack of understanding of His nature and purposes, and a subsequent lack of confidence in Him. The shifting sands of shallow or faulty theology provide no stable footing for the believer.
Anxious, fretful, worried, harried believers are inherently unstable and vulnerable to trials and temptations. Anxiety is both a violation of Scripture and totally unnecessary. In a magnificent passage in the Sermon on the Mount, Jesus pointed out the sinful folly of anxiety:
For this reason I say to you, do not be worried about your life, as to what you will eat or what you will drink; nor for your body, as to what you will put on. Is not life more than food, and the body more than clothing? Look at the birds of the air, that they do not sow, nor reap nor gather into barns, and yet your heavenly Father feeds them. Are you not worth much more than they? And who of you by being worried can add a single hour to his being worried can add a single hour to his life? And why are you worried about clothing? Observe how the lilies of the field grow; they do not toil nor do they spin, yet I say to you that not even Solomon in all his glory clothed himself like one of these. But if God so clothes the grass of the field, which is alive today and tomorrow is thrown into the furnace, will He not much more clothe you? You of little faith! Do not worry then, saying, “What will we eat?” or “What will we drink?” or “What will we wear for clothing?” For the Gentiles eagerly seek all these things; for your heavenly Father knows that you need all these things. But seek first His kingdom and His righteousness, and all these things will be added to you. So do not worry about tomorrow; for tomorrow will care for itself. Each day has enough trouble of its own. (Matt. 6:25–34)
Harmony in the fellowship, joy in the Lord, contentment in circumstances, and confident trust in God are the first steps on the path to spiritual stability.
Spiritually stable people react to trials with thankful prayer. Such prayer is the antidote to worry and the cure for anxiety. The theology of prayer is not in view here, but rather its priority and the attitude the believer brings to it. The three synonyms used here, prayer, supplication, and requests, all refer to specific, direct offerings of petition to God. The assumption of the text is that believers will cry out to God when they have a need or a problem, not with doubting, questioning, or even blaming God, but with thanksgiving (cf. Col. 4:2). Instead of having a spirit of rebellion against what God allows, believers are to trustingly cast “all [their] anxiety on Him, because He cares for [them]” (1 Peter 5:7).
God’s promises support the wisdom of gratitude. He has promised that no trial believers face will be too difficult for them to handle (1 Cor. 10:13). He has also promised to use everything that happens in believers’ lives for their ultimate good (Rom. 8:28). Even suffering leads to their being perfected, confirmed, strengthened, and established (1 Peter 5:10). Believers should also be thankful for God’s power (Ps. 62:11; 1 Peter 1:5; Rev. 4:11), for His promises (Deut. 1:11; 2 Cor. 1:20), for the hope of relief from suffering (2 Cor. 4:17; 1 Peter 5:10), for the hope of glory (Rom. 5:2; Col. 1:27), for His mercy (Rom. 15:9), and for His perfecting work in them (Phil. 1:6).
People become worried, anxious, and fearful because they do not trust in God’s wisdom, power, or goodness. They fear that God is not wise enough, strong enough, or good enough to prevent disaster. It may be that this sinful doubt is because their knowledge of Him is faulty, or that sin in their lives has crippled their faith. Thankful prayer brings release from fear and worry, because it affirms God’s sovereign control over every circumstance, and that His purpose is the believer’s good (Rom. 8:28).
MacArthur New Testament Commentary