Our Scripture reading today is 1 Peter 5:8-10.
Verse 8, "Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:"
We are will aware of how powerful our enemy is.  He is compared in this verse to the king of the jungle.  Other places in Scripture refer to him as the "prince of the power of the air" (Ephesians 2:2).  "He is a finite being and can only be in one place at one time, yet his effort, energy, and associates enable him to extend his influence all over the world and in every arena of life."  It would be very foolish to attempt to overcome his power and might in the strength of our flesh.
The Apostle Peter exhorts us to be sober and vigilant.  We are to be on guard every day we live.  Our enemy does not take a day off from trying to devour us.  He could be just around the corner.  Therefore, it is imperative that our heart and mind continue to be cleaned and filled with the Word of God.  As our faith is strengthened by God's Word, we will be able to resist his temptations.  James 4:7, "Submit yourselves therefore to God. Resist the devil, and he will flee from you."