This year, the people of the Middle East have lived under the same sky of fire. Missiles have fallen on Riyadh’s neighbors and on Tel Aviv, on Dammam and on Haifa. Families in the Gulf, in Israel and, above all, in Gaza and the West Bank have buried loved ones and comforted frightened children. Whatever divides us, we have been reminded — brutally — of what we share: vulnerability, grief and the stubborn hope that our children might inherit something better. I write these words as an American Jew, the head of a global Jewish organization and someone who spent years in American public life.