Have you ever stopped to ask yourself what it is you are trying to accomplish as a parent? What exactly is your objective? Since you are a Christian parent there is only one ultimate answer to this question--and that answer is found in the Bible. The supreme objective you should have for your children is the same objective the Apostle Paul had for his spiritual children--that they be conformed to (gradually changed into) the image of Christ.
My children, with whom I am again in labor until Christ is formed in you... (Gal. 4:19)
The Bible describes this "Christ-likeness" in a variety of ways. Terms such as "perfect" or "complete," "sanctification," and "the measure of the stature which belongs to the fullness of Christ" (to name a few) are employed by Paul (and other New Testament authors) to communicate a heartfelt desire to see those under his spiritual care attain the goal of Christian maturity.
And we proclaim Him admonishing every man and teaching every man with all wisdom, that we may present every man complete in Christ. (Col. 1:28)
Until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a mature man, to the measure of the stature which belongs to the fullness of Christ. As a result, we are no longer to be children, tossed here and there by waves, and carried about by every wind of doctrine, by the trickery of men, by craftiness in deceitful scheming; but speaking the truth in love, we are to grow up in all [aspects] into Him, who is the head, [even] Christ. (Eph. 4:13-15)
How wonderful! Your objective (that which you are attempting to accomplish) as a parent has already been laid out for you in the Bible. You don't have to wonder what your child should become. You know what your child is supposed to look like when you're finished training him. He is to look like Jesus Christ.
There are at least three essential ingredients necessary to produce the Christ-like maturity you are to be endeavoring to produce in your children. They are the Spirit, the Scriptures, and time. First it is necessary for a person to be changed into the image of Christ by the Holy Spirit. This gradual transformation takes place on the inside of a person--in his heart. The Holy Spirit indwells only those individuals who have, by God's grace, trusted in the atoning work of Christ Who died on the cross (as a substitute) for (to pay the penalty for) their sins (Rom. 5:87; 1 Cor. 15:3; 2 Cor. 5:21). You, too, must depend on God's Spirit to help you become the kind of parent the Bible requires of you.
The second maturity-producing resource is the Bible. Now the interesting thing to note is that the Scriptures are necessary to help your child realize the basics of salvation, such as his sinful condition and his need to trust in Christ's substitutionary death on the cross. You see, no one can become a Christian without the Bible (cf. Rom. 10:13-17). The Spirit works through the Word to bring conviction and ultimately regeneration (1 Peter 1:23). Because the Scriptures are able (have the power) to make your children wise about salvation, it is essential that you begin using the Scriptures with your children at an early age.
...and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus. (2 Tim. 3:15)
Charles Spurgeon, in his book Come Ye Children: A Book for Parents and Teachers on the Christian Training of Children, addresses the term "from a child."
The expression, "from a child," might be better understood if we read it, "from a very child;" or, as the Revised Version has it, "from a babe." It does not mean a well-grown child, or youth, but a child just rising out of infancy. From a very child Timothy had known the sacred writings. This expression is, no doubt, used to show that we cannot begin too early to imbue the minds of our children with Scriptural knowledge. Babes receive impressions long before we are aware of the fact. During the first months of a child's life it learns more than we imagine. It soon learns the love of its mother, and its own dependence; and if the mother be wise, it learns the meaning of obedience and the necessity of yielding its will to a higher will. This may be the key-note of its whole future life. If it learn obedience and submission early, it may save a thousand tears from the child's eyes, and as many from the mother's heart. A special vantage-ground is lost when even babyhood is left uncultured.
The Holy Scriptures may be learned by children as soon as they are capable of understanding anything.