Sarah Hurwitz calls her first book, “Here All Along,” a “love letter” to Jewish tradition. Describing a journey begun when she worked as a speechwriter at the White House— first for President Barack Obama and later for First Lady Michele Obama — the book was a celebration of her rediscovering Judaism as a thirty-something who grew up with what she describes as a “thin” Jewish identity. But if that book was sunny, her new book explores the shadows and storm clouds of Jewish belonging. “As a Jew: