What does that have to do with "playing god"? That's asking for the actual one to intervene.

For the sentence about prayer, he may have meant, that those people might also consider using of modern medicine a form of playing god. Because prayer could have cured the illness.

For the second line about Greeks, it's more about Spartans. See http://www.historywiz.com/didyouknow/spartanfamily.htm