As believers face a wide range of spiritual evil, Paul reminds them that these tools are critical to their survival. Rather than having a selection of items from which to choose, God's armor comes as a package. It is essential that we have salvation and the Word of God. Neither prayer nor righteousness can be achieved without the other. To be effective, each of these areas must work in concert.
As Christians, we are called to take up our weapons of warfare and to put on the full armor of God. This is another way of saying clothe yourself in the Lord Jesus Christ. In his letter, Paul urges believers to put on Christ, to abide in Christ, and to rest in Him just as He abides in us. No compromise should be made with the ways of the world, nor should we be deceived by the darkness of our fallen age. 
As members of Christ's spiritual army, may we be faithful to fulfill our privileged position? It is not a good idea to try to fight the enemy using your own strength or self-righteous pride. Rather, we must put on our heavenly armor as we pray in the Spirit and remain protected in Christ, who is our refuge and strength.

Dear Heavenly Father, I know that my security in You is grounded in the Gospel, the death, burial, and resurrection of Jesus Christ. In this evil day on which we live, I pray that I will take up God's armor and resist the enemy's plots. Being clothed in Christ's righteousness, I pray that I may walk in spirit and truth. Let Your power be with me in this evil day so that I can stand fast and resist the principalities and powers. 
In Jesus's name I pray. Amen.