THIS MIGHT SURPRISE YOU
The answer
A sling and a single stone (1 Samuel 17:49). Then — the part often forgotten — David finishes the job with Goliath's own sword (1 Samuel 17:51).
Why it’s interesting
The sling wasn't a toy; ancient slingers were feared skirmishers who could kill at distance. But that isn't the point the narrator is making — at 17:45-47 David says the battle is the LORD's, and that deliverance doesn't come by sword or spear.
Scholarly consensus
You can know the Bible.
Not just the stories, but the history, authorship, and scholarship behind it.