The word ‘baptizo’ in Greek has the following three things associated with it.
to dip repeatedly, to immerse, to submerge
to cleanse by dipping or submerging, to wash, to make clean with water, to wash one’s self, bathe
to overwhelm
This then is what the early church had in mind when they heard the word. Being immersed in water was the usual baptism practice of the early Christians. The idea of being submerged and overwhelmed symbolised a believer’s desire to be totally immersed in the things of God. It was a show of allegiance that they were all in for Jesus.