Proverbs 22:6 has caused many righteous parents, over the years, to question their righteousness, or even their conversion, when their children who had been trained in the way of righteousness and truth later departed from it. They concluded that it must have been their fault that their children did not stay loyal to God.
However, a close look at Proverbs 22:6 might reveal that the righteous parents caused unnecessary grief for themselves in this matter (Of course, we must also realize that many parents who thought that they were converted Christians might not have been converted at all, which might be evidenced by the fact that they later left the Way of Truth, compare 1 John 2:19).
1 Corinthians 7:14 reads, "For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband; otherwise your children would be unclean, but now they are holy."
The Ryrie Study Bible gives the following correct explanations of this passage:
"The presence of a believer in the home sets the home apart and gives it a Christian influence it would not otherwise have. A believing partner, therefore, should stay with the unbeliever. However, this does not mean that children born into such a home are automatically Christians. They are holy in the sense of being set apart by the presence of one believing parent."
"You are the light of the world. A city that is set on a hill cannot be hidden."
-Matthew 5:14