Summary: 1) The Preparation (Ephesians 6:10), 2) Armor (Ephesians 6:11a), 3) Enemy (Ephesians 6:11b), 4) Battle (Ephesians 6:12), and 5) The Victory of the Believer’s Warfare (Ephesians 6:13).
Major-General Sir Ernest Swinton, used to speak on the radio once each week as a military commentator from September 1939 onwards. Nothing seemed to be happening, no guns were being fired, there had been no clash of arms, no air-raids had taken place, the war seemed dead. But Sir Ernest Swinton kept on saying each week, ‘We are fighting for our lives.’ He seemed to many to be a pessimist; but he kept on saying it. ‘Make no mistake about it,’ he used to say, ‘we are fighting for our very lives.’ And he continued to say it though nothing was happening. The fact was that he knew something about the power and the subtlety of the enemy; he knew what was happening. He knew that this apparent lull was most deceptive, and that if we were wise we would be preparing with all our might and main. He knew that the terrible onslaught was bound to come. And of course warfare did come! (Lloyd-Jones, D. M. (1976). The Christian Warfare: An Exposition of Ephesians 6:10–13 (pp. 96–97). Edinburgh; Carlisle, PA: Banner of Truth Trust.)
The true Christian described in Ephesians 1–3 who lives the faithful life described in 4:1—6:9 can be sure that they will be involved in the spiritual warfare described in 6:10–20. The faithful Christian life is a battle; it is warfare on a grand scale—because when God begins to bless, Satan begins to attack. In this letter, Paul explained the need for unity in the body of believers; here he further explained the need for that unity—there will be inevitable clashes with evil, and the church must be ready to stand and fight (Barton, B. B., & Comfort, P. W. (1996). Ephesians (p. 127). Wheaton, IL: Tyndale House Publishers.).
If we are walking worthy of our calling, in humility rather than pride, in unity rather than divisiveness, in the new self rather than the old, in love rather than lust, in light rather than darkness, in wisdom rather than foolishness, in the fullness of the Spirit rather than the drunkenness of wine, and in mutual submission rather than self–serving independence, then we can be absolutely certain we will have opposition and conflict.
Recognizing Satan’s schemes, Paul closes his letter to Ephesus by giving his brothers and sisters there both encouragement and warning, much as Jesus did in His letters to the seven churches of Asia Minor over 30 years later. In Ephesians 6:10–13 the apostle outlines the necessary information in regard to 1) The Preparation (Ephesians 6:10), 2) Armor (Ephesians 6:11a), 3) Enemy (Ephesians 6:11b), 4) Battle (Ephesians 6:12), and 5) The Victory of the Believer’s Warfare (Ephesians 6:13).
1) The Preparation: Strength in the Lord
Ephesians 6:10 Finally, be strong in the Lord and in the strength of his might. (ESV)
Basic to the effective Christian life is preparation. The unprepared believer becomes the defeated believer who seeks to serve the Lord in their own wisdom and power. The strength of the Christian life is dependence on God, being strong. The passive voice would suggest that we cannot do it ourselves (Radmacher, E. D., Allen, R. B., & House, H. W. (1997). The Nelson Study Bible: New King James Version (Eph 6:10). Nashville: T. Nelson Publishers.).
We are to be strong: in the Lord, and in the strength of His might. Any other strength proves to be impotent. To ‘be strong’, is best understood as a passive, meaning ‘be made strong, be strengthened’ (O’Brien, P. T. (1999). The letter to the Ephesians (p. 460). Grand Rapids, MI: W.B. Eerdmans Publishing Co.).
Furthermore, he says, not ‘by the Lord’, though that would be true enough, but again in the Lord. When life is lived in union with him, within the orbit of his will and so of his grace, there need not be failure due to powerlessness (1 John 2:14). Apart from him the Christian can do nothing (John 15:1–5), but there is available all the strength of his might (Foulkes, F. (1989). Ephesians: an introduction and commentary (Vol. 10, pp. 175–176). Downers Grove, IL: InterVarsity Press.).
The cardinal reality presented in the book of Ephesians is that, as believers, we are in Christ and are one with Him. His life is our life, His power our power, His truth our truth, His way our way, and, as Paul goes on to say here, His strength is our strength. The Lord’s strength is always more than sufficient for the battle. When Jesus told the church at Philadelphia, “I have put before you an open door which no one can shut, because you have a little power, and have kept My word, and have not denied My name” (Rev. 3:8), He was affirming that even a little power was enough to preserve them, because it was the Lord’s supernatural power. Our own strength is never strong enough to oppose Satan, but when we are strong in the Lord, even a little of His strength is sufficient to win any battle. “I can do all things through Him who strengthens me,” Paul said (Phil. 4:13). It is not the amount of the strength we have that is important—only its source.