Seeing how John Piper’s kids turned out, he’s the last person in the world I would turn to for advice on raising kids - he’s not even qualified to be an elder - just sayin ...
Neither is a divorced man qualified to be an elder, if one applies the Word as written: A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach[.]" I Timothy 3:2 AKJV (emphasis added).