Secretary of State John Kerry has made a significant mistake in how he’s pursuing a Gaza cease-fire — and it’s not surprising that he has upset both the Israelis and some moderate Palestinians. Kerry’s error has been to put so much emphasis on achieving a quick halt to the bloodshed that he has solidified the role of Hamas, the intractable, unpopular Islamist group that leads Gaza, along with the two hard-line Islamist nations that are its key supporters, Qatar and Turkey.