"Put on the whole armor of God, that ye may be able to stand against the wiles of the devil." (Eph. 6:11)
We are armed for victory. Putting on the panoply of God is the only way we can be guaranteed of winning the spiritual battle. The idea of standing is that we don't lose ground to Satan and his forces.
"In the day of battle, Roman soldiers were to stand their ground, not retreat. As long as they stood together on a flat, open field and did not break ranks, their legions were considered virtually invincible." (C. Keener - IVP Bible Background Commentary).
The word 'wiles' means scheme or "trickery" (Stong). Satan has stratagems and methods whereby he plots to defeat Christians who are ill prepared via neglegence in putting on the whole armor of God. Therefore, putting on God's complete armor is not an option, it is an imperative, it is an absolute necessity.
William Gurnall in his classic work "The Christian in Complete Armour" says: "Satan with all his wit and wiles, will never defeat a soul armed with true grace nor will the contest end in a stalemate." And how true that is.