Is Oratorio Drama?

Could you explain the moral difference between drama and oratorio?  Maybe I should explain my question. I've sung in several oratorios which required the chorus to sing an evil crowd chorus (e.g., "Let Him deliver Him" in Handel's Messiah, "Baal, We Cry to Thee" in Mendelsshon's Elijah, and "Crucify" from Bach's Passion According to St. John. Such choruses hold essential meaning for the overall message, but they require the singer to imitate evil. (I have the same dilemma regarding effective...