Must a Pastor-Elder's Children be "Faithful" (in obeying parents) or "Believing" (in Christ)?

I'm preaching on Titus 1:5-9 this Sunday. Here's one of the questions raised in the passage that I may not have time to get into: "Must a Pastor-Elder's Children be "Faithful" (in obeying parents) or "Believing" (in Christ)?"

Here are different takes on it:

John MacArthur believes the children must savingly believe: "[It] may be that you as a father have made every effort, every good and righteous effort possible to lead your children to faith in Christ and you have not seen the fruit that you would desire. You are not responsible for your child's rejection before God but neither would you be qualified to be an elder or a pastor in the church." He writes in his commentary on Titus that "faithful" is used of God, his words, and people in general.

"But it is significant that , except for this sometimes disputed text, it always is used of people whom the context clearly identifies as believers. Unbelievers are never referred to as faithful. That fact alone argues strongly for the rendering here of children who believe, that is, who have placed their faith in Jesus Christ. Even if the idea were of faithfulness to patents, the use of pistos in those other passages would argue for its referring to the faithfulness of believing children. In an elder's home, especially, a child who is old enough to be saved, but is not, can hardly be considered faithful. He would be unfaithful in the most important way" (30).

He goes on to say that if the children are too young then 1 Timothy 3 applies and as they grow older "the issue is no longer control, the more demanding criteria of Titus 1 comes into play" (30).

John Piper, Justin Taylor, Matt Schmucker, D. A. Carson, and Andreas Kostenberger take it to mean "faithful."

Here's Carson's take on it (though I'd refer you to Taylor or Kostenberger for more substantial arguments since Carson's comes from a sermon that was much broader in scope):

I think it is mistranslated in the NIV. The NIV renders Titus 1:6, "An elder must be blameless, the husband of but one wife, a man whose children believe and are not open to the charge of being wild and disobedient." Does this mean that the children of every leader must be Christians? And if you say yes, then from what age? Two? Five? Seventeen? In fact, the particular term that is used there, "must believe," is an adjective that in many places is rendered "must be faithful." And in fact, in contemporary first-century lists of social virtues, where moral characteristics are laid out, the word always has that force. I think that what the text is saying is not that the children must be saved – after all, grace doesn’t run in the genes – but that at the end of the day, they must be faithful, not wild or profoundly disobedient.

I think it means faithful and refer you to the links above to hear or read why.