You’ve made a decision to follow Christ.

Now what?  What ethic do you live by?  The Ten Commandments?  Poor Richard’s Almanac?  In several places in the New Testament we are taught to live the Christian life by what the old time theologians called mortification and vivification.  That is, by consciously putting off our old, sinful nature, and putting on our new Christ-like nature. As the great London pastor Charles Spurgeon once preached, “every new man is two men; every believer in Christ is what he was, and not what he was: the old nature, and the new nature exist at the same time in each regenerate individual…I am much mistaken if every Christian does not find this old man still troubling him.”

It’s critical to realize that when you become a Christian there’s more to it than just making a decision. It’s not like going from an SUV to a minivan, for example (although that decision too is not without its psychological effects).  When you become a Christian you are immediately a different person, or what the Bible calls a new creation. Your old nature is dead.  Romans 6:6 says that for the believer our old self has been crucified with Jesus. Yet our old nature, though dead, remains with us as long as we are in this body.

Paul puts it this way in Romans 6:3: “Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death?”  Baptism, in fact, is the perfect illustration for what has already happened to the born-again Christian: the old nature buried with Jesus in his death (going down into the water), the new person then raised with Christ in his resurrection (coming back up).

As the grisly term mortification implies, as Christians we should not be content with merely brushing off our sinful nature, as one shoos away a fly.  No, we are to put it to death.  The 16th century Reformer John Calvin said that “the very name mortification reminds us how difficult it is to forget our former nature.”  But Colossians 3:5 puts it like this: “Put to death therefore what is earthly in you.”  Why should we put our old nature to death? Well, Romans 6:6-7 tells us that we have been crucified with Christ so that “we would no longer be enslaved to sin. For one who has died has been set free from sin.”  Why continue to live under the enslaving, killing power of our harsh former master when we have already been set free from it?

So put off and put on.  Put off your sinful nature, put on your heavenly one.  Put off by turning away from the sin that once enslaved you.  Put on by looking to Christ, and adopting the heavenly qualities found in Colossians 3:12-17. In short, to quote Spurgeon again, “live nearer to Christ! All virtues flourish in the atmosphere of the cross; all vices die beneath the shade of the cross—but get away from your Master, and you will be undone.”

At death your sin nature will be done away with forever. It’s not worth indulging it a minute longer. Your new nature, on the other hand, will be yours forever.  And you will come to resemble Jesus more and more as you put the old off, and put the new on.