Being unthankful is the very essence of the unregenerate heart. The apostle Paul identified unbelievers as ungrateful: "For even though they knew God [through conscience and general revelation], they did not honor Him as God or give thanks, but they became futile in their speculations, and their foolish heart was darkened" (Rom. 1:21). But when God regenerates an individual, He produces a new heart that longs to obey Paul's injunction and in everything give thanks. That simple, direct statement allows believers no excuses to be ungrateful. In everything (en panti) refers to all that occurs in life. No matter what struggles, trials, testings, or vicissitudes occur in the lives of Christians (with the obvious exception of personal sins), they are to give thanks (Acts 5:41; cf. James 1:2--3; 1 Peter 1:6--9). Thankfulness therefore should be part of the fabric of the regenerate life (Ps. 136:1--3; Dan. 6:10; Eph. 5:20; Col. 3:17; Heb. 13:15), a gracious fruit of the Holy Spirit's work within the believer's heart (cf. Col. 2:7).
It is spiritually abnormal for Christians to be unthankful. Unthankfulness disobeys the many Scripture texts that enjoin the believer to a life of gratitude. Romans 8:28 sets forth the overarching principle: "And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose." God's providence—His sovereign blending of all of life's contingencies for believers' ultimate blessing—causes them to be thankful for everything in life, knowing that it fits into His eternal purpose for them (cf. Gen. 50:20; Pss. 37:28; 91:3--4; 145:9; Prov. 19:21).
Even in times of great anxiety, fear, worry, and stress, a prayerful attitude of thanksgiving should characterize believers (Phil. 4:6--7).
Paul's statement, for this is God's will for you in Christ Jesus, attaches to all three commands in this passage. It is God's will that all those who are in Christ Jesus should express constant joy, constant prayer, and constant thanksgiving. And God not only mandates those expressions of righteousness, but He makes it possible for believers to articulate them (cf. Phil. 2:13)—and is pleased when they do...