“Careless talk costs lives,” proclaimed a campaign by the British Government during the Second World War. The government wanted people to be aware of the danger around them: that listening enemy ears were ready to pounce on any slip of the tongue.

Here, Paul gives us a similar warning for our Christian lives: carelessness can cost lives. Carelessness makes us susceptible to danger. So many of us live carelessly when it comes to our spiritual lives, walking about in a kind of moral dream, failing to stay awake and alert to the dangers around us. That leaves us vulnerable. Consider just two reasons why it is vital that we stay awake and alert in our pursuit of purity.

First, the apostle Peter tells us, “Your adversary the devil prowls around like a roaring lion, seeking someone to devour” (1 Peter 5:8). Let’s not kid ourselves: sin is predatory. The enemy is a lion. Recall the way the Lord spoke to Cain when he was angry with his brother: “Sin is crouching at the door. Its desire is contrary to you, but you must rule over it” (Genesis 4:7).

Do you know who makes for easy prey? An isolated Christian. When we’re isolated, we’re vulnerable and without accountability. We “walk properly” most easily in godly company. As children of the daytime, we must not be lured by the darkness, because darkness creates isolation. A passion for purity demands that we walk in the light and with the children of light.

Second, we must stay awake and stay alert because eternity awaits. What is it that made the heroes of Hebrews 11 worthy of the title “heroes”? They were looking for a city beyond them. They looked for a city whose foundation and builder was God (Hebrews 11:10).

Moses, for example, did not succumb to the lure of instant gratification. He did not sell his soul for the moment. He did not give up his ministry, future, and family for comfort and privilege. He chose instead a more difficult course. And what was the explanation? “He considered the reproach of Christ greater wealth than the treasures of Egypt, for he was looking to the reward” (v 26). Moses was not without blemish, and neither are we. But that must not excuse us from living for the sake of Christ in matters of purity. After all, our salvation is drawing ever closer, and we want to be found ready for the Lord Jesus when He appears.

Whatever your past has been, whatever your recent mistakes and disappointments, it’s not too late to wake up and stay alert. The enemy will not sleep, and eternity will be worth it. Ask God today to write a commitment on your heart to a life of purity, so that today you would walk properly and carefully, with your head up and your eyes fixed on that glorious future day of your salvation.