John Stott's Bible Speaks Today commentary on Ephesians has the following quote on the work of the devil. It was reading the last paragraph of this quote that gave me the idea of how to approach Ephesians 6 in the sermon I will be preaching this morning:

“We have had occasion several times in our study of this letter to marvel at the breadth of Paul’s horizons. He began by unfolding God’s purpose, conceived in a past eternity before the foundation of the world, to create a single new human race through the death and resurrection of Christ and ultimately to unite the whole church and the whole creation under Christ’s headship . . .

The old days of division and discrimination have gone. A brand new oneness has emerged, in which through union with Christ Jews and Gentiles are equal members of the same body and equal sharers in the same promise. So now the one Father has one family, the one Messiah-Saviour one people, and the one Spirit one body. These sure facts of what God has done through Christ and by the Spirit form the basis on which Paul went on to issue his eloquent appeal. His readers must live a life that is ‘worthy’ of their calling and ‘fitting’ to their status as God’s new and reconciled society. They must demonstrate their unity in the Christian fellowship, while at the same time rejoicing in the diversity of their gifts and so of their ministries. They must put away all the uncleanness of their pre-conversion behaviour and live a life of ‘true righteousness and holiness’. And they must learn to submit to one another in every kind of domestic relationship and so promote harmony in their homes. Unity, diversity, purity and harmony—these the apostle has stressed as major characteristics of the new life and the new society in Christ. It has seemed a beautiful ideal, an obviously desirable goal, and not so difficult to attain.

But now Paul brings us down to earth, and to realities harsher than dreams. He reminds us of the opposition. Beneath surface appearances an unseen spiritual battle is raging. He introduces us to the devil (already mentioned in 2:2 and 4:27) and to certain ‘principalities and powers’ at his command . . .

Is God’s plan to create a new society? Then they will do their utmost to destroy it. Has God through Jesus Christ broken down the walls dividing human beings of different races and cultures from each other? Then the devil through his emissaries will strive to rebuild them. Does God intend his reconciled and redeemed people to live together in harmony and purity? Then the powers of hell will scatter among them the seeds of discord and sin.”

Stott, J. R. W. (1979, 1980). God's New Society : The Message of Ephesians (260). Downers Grove, IL: InterVarsity Press.