Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. For we wrestle not against flesh and blood, but against the principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places. Ephesians 6:11, 12.
It is not safe for us, when going into battle, to cast away our weapons. It is then that we need to be equipped with the whole armor of God. Every piece is essential.1Testimonies for the Church 7:190.
While Satan is constantly seeking to blind their minds to the fact, let Christians never forget that they “wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against wicked spirits [margin] in high places.” The inspired warning is sounding down the centuries to our time: “Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour.” …
From the days of Adam to our own time our great enemy has been exercising his power to oppress and destroy. He is now preparing for his last campaign against the church. All who seek to follow Jesus will be brought into conflict with this relentless foe. The more nearly the Christian imitates the divine Pattern, the more surely will he make himself a mark for the attacks of Satan.2The Great Controversy, 510.
We must have on the whole armor of God, and be ready at any moment for a conflict with the powers of darkness. When temptations and trials rush in upon us, let us go to God, and agonize with Him in prayer. He will not turn us away empty, but will give us grace and strength to overcome, and to break the power of the enemy. Oh, that all could see these things in their true light, and endure hardness as good soldiers of Jesus! Then would Israel move forward, strong in God, and in the power of His might.3Early Writings, 46.