From these words, John 3.23, it may be inferred, that baptism was administered by John and Christ by plunging the whole body under water. Here we perceive how baptism was administered among the ancients; for they immersed the whole body in water.Luther:
The term baptism is a Greek word. It may be rendered immersion, as when we plunge something in water, that it may be entirely covered with water. And though that custom is now abolished among the generality [for even children are not entirely immersed, but only have a little water poured on them] nevertheless, they ought to be completely immersed, and immediately drawn out. For the etymology of the word evidently requires it.