Waiting for a heart change

I've read Raising Godly Tomato's Separation article and I am painfully aware of raising children to be "in the Lord" after 18. However, I don't think it is a matter of separating from the world.

I think the key is to pray for and wait for a heart change to take hold of the child in question. Just as passion for an academic topic will carry through a child for a long time, a passion for Christ is needed for the child to carry through for a life time. This heart change cannot be induced by parents, no matter how hard one tries. It can only come when the child opens up to God and the influence of the Holy Spirit. Parents can set examples and pray for this change but waiting is the only thing left for the parents, I believe.

I'm sure less distraction of the world would help but complete isolation won't solve this problem of heart change.