Train them, remembering continually the power of sin.
I name this shortly, in order to guard you against unscriptural expectations. You must not expect to find your children’s minds a sheet of pure white paper, and to have no trouble if you only use right means. I warn you plainly you will find no such thing. It is painful to see how much corruption and evil there is in a young child’s heart, and how soon it begins to bear fruit. Violent tempers, self-will, pride, envy, sullenness, passion, idleness, selfishness, deceit, cunning, falsehood, hypocrisy, a terrible aptness to learn what is bad, a painful slowness to learn what is good, a readiness to pretend anything in order to gain their own ends — all these things, or some of them, you must be prepared to see, even in your own flesh and blood. In little ways they will creep out at a very early age; it is almost startling to observe how naturally they seem to spring up. Children require no schooling to learn to sin.
But you must not be discouraged and cast down by what you see. You must not think it a strange and unusual thing, that little hearts can be so full of sin. It is the only portion which our father Adam left us; it is that fallen nature with which we come into the world; it is that inheritance which belongs to us all. Let it rather make you more diligent in using every means which seem most likely, by God’s blessing, to counteract the mischief. Let it make you more and more careful, so far as in you lies, to keep your children out of the way of temptation.
Never listen to those who tell you your children are good, and well brought up, and can be trusted. Think rather that their hearts are always inflammable as tinder. At their very best, they only want a spark to set their corruptions alight. Parents are seldom too cautious. Remember the natural depravity of your children, and take care.