"It is an experimental truth that ought never to be overlooked, that when a believer has once begun to back-slide and leave his first faith, he seldom stops short at his first mistake. He seldom makes only one stumble. He seldom commits only one fault. A blindness seems to come over his understanding. He appears to cast over-board his common sense and discretion. Like a stone rolling down-hill, the further he goes on in sinning, the faster and more decided is his course. Like David, he may begin with idleness, and end with committing every possible crime. Like Peter, he may begin with cowardice — go on to foolish trifling with temptation, and then end with denying Christ.
If we know any thing of true saving religion, let us ever beware of the beginnings of backsliding. It is like the letting out of water, first a drop and then a torrent. Once out of the way of holiness, there is no saying to what we may come. Once giving way to petty inconsistencies, we may find ourselves one day committing every sort of wickedness. Let us keep far from the brink of evil. Let us not play with fire. Let us never fear being too particular, too strict, and too precise...'Lead us not into temptation.'"
JC Ryle, Expository Thoughts on the Gospels, 2.258.