We have a natural tendency to slip back into our old sinful ways. I have a natural tendency to do what's wrong. But then I have a supernatural tendency to do what's right.
We can compare our tendencies to a flower and a weed. A weed is like our old natures - that part of us that doesn't want to obey God. The flower is like our new natures. My wife loves to plant flowers. She tends them and cares for them. She puts snail repellent down, picks any weeds that get even remotely close, fertilizes them, and watches over them. But I've noticed a rather strange phenomenon. In the same time it takes for that beautiful little flower to grow two inches, a new weed bursts through some crack in the street and grows about eighteen feet high! How much nurturing did the weed need? None.
Like the fragile flower, the new nature needs nurturing. It needs encouraging. As believers we need to do the things that build us up spiritually. The old nature, however, needs little or no encouragement. If we neglect spiritual growth, we will be shocked by how quickly and easily we can be pulled in the wrong direction. - Greg Laurie, The God of the Second Chance, p. 61