"Be on your guard and stay awake. Your enemy, the devil, is like a roaring lion, sneaking around to find someone to attack" (1 Peter 5:8, Contemporary English).
Viewed in light of the previous verses, the advice given here is profoundly important. Peter is showing us that if we let fears, worries, anxieties, and feelings of dread pull us in several directions at the same time -- taking our focus away from the Lord who cares for us -- then our lives will be ripped to pieces, leaving us open to the insidious attacks of the devil.
Now, for the record, the devil is NOT a roaring lion; he likes to THINK he is.
There is only One Lion -- the Lion of the Tribe of Judah. And the Devil has been trying to usurp His authority from the beginning. So now he pretends to be a lion, roaring about the land in search of someone to attack.
But he only has access into our lives when we look away from the Lord and began to overthink our fears, worries, anxieties and dreads. In this state of distraction we unwittingly offer the devil our unguarded hearts -- and he ravages us with lies and accusations.
Yet, even then, the Lord still is our Savior. He rebukes the devil and reclaims our fractured lives; healing us, and making us whole once more. And thus we sing the song of the redeemed -- "If the Lord had not been on our side, all our enemies would have swallowed us alive!" (see Psalm 124)
The best thing is for us to take Peter's counsel and thereby preempt anything the devil is scheming to do. By casting our cares upon the Lord, we are free from fear, worry, anxiety and dread. In that freedom we stand vigilant, guarded, prepared, and victorious.
"Be sober, sensible and on your guard, clear-headed and well balanced; fully awake and keeping watch; vigilant and guarded at all times. You have a great adversary, the sneaky devil, who prowls about as a roaring lion seeking someone to attack, seize and devour. Keep a cool head; he is poised to pounce, and would like nothing better than to catch you napping." (1 Peter 5:8, composed from several translations).