When the devil had finished tempting Jesus, he left him until the next opportunity came. (Luke 4:13 NLT)
The devil is just waiting for the "next opportunity" to come along to trip you up spiritually or destroy your life totally. That's why as followers of Jesus Christ we can never let down our guard even for a moment. As soon as he sees an opening to reek havoc in our lives he will pounce on us with all the feirceness of a "roaring lion." Knowing this should help you better understand Paul's words, "...and do not give the devil an opportunity." (Ephesians 4:27 NASB)
