Jews baptized proselytes.[1] The periodically repeated Jewish purification rite of mikvah is not normally spoken of as baptism, largely because of the Christian associations of the word "baptism".
The Greek-English Lexicon of Liddell and Scott gives the primary meaning of the word βαπτίζω (transliterated as "baptizô"), from which the English word baptism is derived, as dip, plunge, but indicates, giving Luke 11:38 as an example, that another meaning is perform ablutions.
The specific practices of Ablution in Christianity are generally concerned with either ritual purification, or symbolism of humility.
In Exodus 19:10 it is written: "And the LORD said unto Moses, Go unto the people, and immerse/sanctify them to day and to morrow, and let them wash their clothes"
As you can see G-d commanded the people to prepare themselves for the meeting by
immersion/ritual purification of themselves and their garments.
Yochanan haMatvil/John the Baptist is telling the people to prepare themselves to meet the Messiah and receive the new covenant. The
act of immersion into repentance was necessary for ritual purity.
John the Baptist had been given the same assignment or anointing as Elijah, to prepare the people for the kingdom. As we have seen, those people just as we do today, need a time of reflection and repentance in order to partake of the things of our L-rd, the kingdom of G-d,
just as the people prepared themselves each time to enter the Temple by going through a mikvah. John the Baptist is telling the people they should do the same. Just as the priests were immersed/installed into the priesthood,
we today are kings and priest to our G-d and must be cognizant of our place in holiness. We must remember that the
water does not defile and the water does not purify ... it is
heart attitude. Just as the
niddah and the proselyte had to have intention, so must we.
We can never immerse ourselves enough to wash away our sins. Only the Blood of Yeshua can do that. We will never work our way to heaven by just doing the commandments, we arrive by faith.