What does Exodus 12:29 mean?
Egypt's refusal to release Hebrew slaves has resulted in the tenth (Exodus 7:21; 8:6, 17, 24; 9:6, 10, 24; 10:14, 23) and worst of all plagues. As promised (Exodus 11:4–6), God kills the firstborn of everyone in Egypt. This includes royalty, prisoners, and even livestock. Israel is spared because of their obedience (Exodus 12:28) and faith, applying lamb's blood to their doors (Exodus 12:13).When Moses was young, one of Egypt's kings ordered all male Hebrew babies killed (Exodus 1:16, 22). Now, God is judging Egypt with a similar tragedy. The "firstborn" was the primary heir: usually the oldest male child. In ancient cultures, the firstborn was a family's best hope for the future. For taking the futures of so many Israelites and brutally enslaving the people (Exodus 1:11–14), God gives Egypt a taste of their own evils (Psalm 7:12, 16). The shock and despair of this event will finally break Pharaoh's resolve, and he will grant Israel unconditional release (Exodus 12:31–32).
Details about this stroke of death are limited. Scripture mentions no mechanism for how people died. Nor does the Bible give an explicit time—the Hebrew word translated "midnight" means something more like "in the middle of the night." What is clear is the scope: not a single Egyptian home is spared from loss (Exodus 12:30).