For I know him, that he will command his children and his household after him, and they shall keep the way of the LORD, to do justice and judgment; that the LORD may bring upon Abraham that which he hath spoken of him. (KJV)

The points I want to bring out of this are:
1) the Lord said He knew Abraham. That is relationship. At this time in history, no other man could say that.
2) one of the things God knew about Abraham, was that he would be faithful to teach the Lord's ways to his children and his household. Passing on the heritage of faith is so important. God doesn't have grandchildren, only children.
3) that the Lord's ways are to do justice and judgment. (remembering the the Lord's ways are not our ways [Is. 55:8])
4) The Lord had promised Abraham land and that he would be father of nations. This verse points out that teaching/commanding the Lord's ways would be the way in which the Lord would bring this about.

Faith is certainly more caught than taught. If I just say with my mouth that I love the Lord, but do not act in a way that is consistent with my words, I'll never show my children the way to Christ. Faith is lost in only one generation if it is not passed on. But it carries on for many generations when it is passed on.

Am I saying a person must come from a Christian home in order to be saved? Not at all! The Lord's mercies are new every morning and He desires that all should be saved.

What I am saying is that it is incumbent on Christian parents to teach the ways of the Lord to their children.