The Rev. Richard Mosson Weinberg canceled the Boston ferns and the yellow daffodils for the Easter service ordered for his Episcopal church in Washington’s affluent Kalorama neighborhood. Rabbi Levi Shemtov scrapped plans for the 200-person Seder dinner for Passover in his Chabad synagogue nearby. And Imam Yahya Luqman called off the Ramadan dinners at his mosque down the street.