There are two reasons why we submerge people.
First, that’s how they did it in the Bible. Take John the Baptist, for instance. He wasn’t standing on the shore of the Jordan River with a cup, sprinkling water on people’s heads; he brought them into the river. He was dunking
The Greek word for “baptism” literally meant to plunge, soak, or dip. The English translators didn’t know exactly how to translate that word (or perhaps they were afraid to take a stand), so they just transliterated it. The Greek
baptizo simply became “baptize.”
“Baptism” wasn’t actually a religious word at all. Sometimes they used it for people who drowned or ships that went down at sea. We even have a recipe for pickles recorded by a Greek physician named Nicander. He says, literally,
“bapto (as in, dip quickly) the cucumber in water, and then baptizo (as in, immerse and let it soak) in vinegar.” And then he said, “Your pickle will be filled with the Spirit and speak in tongues.” (Okay, I made that last
Second, we submerge people because of what it symbolizes. When you bury people, you don’t sprinkle dirt on them. You put them into the ground. In baptism, we are being buried with Jesus “by baptism into death, in order that, just as
Christ was raised from the dead by the glory of the Father, we too might walk in newness of life” (Romans 6:4).