The world says, “If it feels good, do it!” and “The ends justify the means.” As a result, we have to be extra alert. It reminds me of God’s message to Sardis in the Book of Revelation. God kept having to tell them to be alert and that must have poured salt into their wounds. You see Sardis was a town that thought it was invincible. It wasn’t, though. Herodotus (In Book 1, Section 84) told about the Telmassians claiming that if King Meles would carry a young lion all the way around the wall, it would magically make the entire city into an impregnable fortress that would never fall. The king carried the lion around the wall, but there was one spot he thought was totally secure because it was on top of a cliff. He didn’t bother to carry the lion by there. Much later, a soldier stood guard on the wall as the city was under siege. It was hot and his helmet fell off and part of the way down the cliff. Rather than face his commanding officers, he climbed partially down the cliff and retrieved the helmet. But the besieging troops saw him do it and realized that the cliff was scalable. Guess where they infiltrated the city and caused the city to fall from within? They sent men up that cliff and exploited Sardis’ weakness.
Paul is speaking to believers who are tempted to compromise. Instead of loving each other, they just want to get along. And when we aren’t actively loving, we are lulled into complacency. We’re in danger of being infiltrated while we’re asleep and being destroyed from within. This verse isn’t talking about being asleep in the sense that some people believe you are when you’re dead (I don’t believe that, but some do.), but it’s talking about believers who have gotten too comfortable, who are too at home in the world.