You, dear friends, must build each other up in your most holy faith.
- Jude 1:20
A sign posted at the end of the road on an airport runway reads, "Keep moving. If you stop, you are in danger and a danger to those who are flying." We could apply the same principle to the Christian life: Keep moving. If you stop, you are in danger.
Why should we keep moving? Because we have a natural tendency to slip back into our old, sinful ways. Just as a car parked on a hill will naturally roll backward when shifted into neutral, we will naturally go the wrong way if we shift our Christian lives into neutral and stop seeking to learn and grow as believers.
Take a flower and a weed for example. Our old nature, that part of us that doesn't want to obey God, is like a weed. Our new nature is like a flower. Now, my wife Cathe loves to grow flowers. She will tend them, care for them, fertilize them, and pull any weeds that get remotely close to them. And in the time it has taken for those flowers to grow a few inches, a weed will have found a crack in the sidewalk and has grown eighteen feet tall. How much nurturing did the weed need? None. It simply took off. Like Cathe's beautiful flowers, our new nature needs nurturing. We need to do the things that will build us up spiritually. But if we cease to do those things, that old nature will come back to haunt us.
The Christian life isn't just about obeying commandments. It is also about wanting to please the Lord, wanting to grow, and wanting to become more like Him.