In the first half of his letter to the Christians at Ephesus (chapters 1-3) Paul the Apostle unveils the glorious truths of God’s sovereign and gracious plan of salvation. His words are all promise, all grace. But Paul’s interest goes beyond merely the power of God to set us free from the penalty of sin. He also calls us to live according to God’s power to free us from the ruling power of sin. God’s grace toward us in Christ extends beyond the gospel’s declarative power. God’s grace to us is also transformative. In other words, the Christian life consists of more than being declared righteous (justification). The Christian life involves walking with the Lord in growing righteousness (sanctification).

Paul begins the letter’s focus on how the Christian must live with the admonition: “I therefore, a prisoner for the Lord, urge you to walk in a manner worthy of the calling to which you have been called…” (4:1). For the remainder of the letter the apostle calls our attention to how God’s saving grace transforms our lives. The attentive reader will recognize the challenge of living such a life in a sinful world where opposition comes not only from other people but from the “spiritual forces of evil in the heavenly places” (6:12). In this final section Paul identifies the opposition. “He introduces us to the devil (already mentioned in 2:2 and 4:27) and to certain ‘principalities and powers’ at his command…His purpose is not to satisfy our curiosity, but to warn us of their hostility and teach us how to overcome them” (Stott, 261).

The central exhortation of this section is “Be strong in the Lord and in the strength of his might” (vs. 10). Notice how Paul calls Christians to be strong but to find their strength in the Lord. One is reminded of the great prayer of Augustine: “Lord, command what you will but give what you command.” The strength by which we must be strengthened is that which belongs not to us, but to the Lord. Paul then likens the strength with which the Lord equips his people to specific articles of armor. Living a life worthy of our calling is not a picnic in the park. It is war. “The peace which God has made through Christ’s cross is to be experienced only in the midst of a relentless struggle against evil. And for this the strength of the Lord and the armor of God are indispensable” (Stott, 263).