The term ὁ βαπτιστὴς is never used in classical Greek. It is only ever used of John. It is a title bestowed upon him by outsiders, just as the title Christian was first bestowed upon the followers of Christ Jesus by outsiders (Acts 11:26). So this title is particular and peculiar to John's ministry. Why was this title bestowed upon him? What significance did it have? What was his ministry about?
"Why then are you baptizing?" John 1:25
"What (baptism), then, do you baptize?" Since Jews in religious rites employed βαπτίζω in the appropriate sense to purify, the question might be modified this way: "What (defilement) do you purify?" Is it an actual removal of ceremonial defilement, or of spiritual defilement? or, is it only a symbol of purification? What is its character? What is its nature? Baptisms are of endless variety, which this passage brings that fact out clearly. The purifying agencies were made up of water, blood, ashes, and fire. There is absolute proof that objects not enveloped by water, blood, ashes, or fire are said to be baptized—ceremonially purified (e.g., Mark 7:4, re: tables/couches).
"I baptize in water." John 1:26
John's answer is perfectly satisfactory: "I baptize with water. Water (of purification, i.e., the symbol of repentance) is the essence of my baptism. My baptism has no other power than that which belongs to simple water, and is therefore merely symbol in its character." His baptism was corporal: Matt. 3:11; Mark 1:8; Luke 3:16—"He will baptize you with the Holy Spirit and fire." John's was a baptism of repentance, whereas Jesus' is a baptism of grace.
John does not merely say Ἐγω βαπτίζω, but Ἐγω βαπτίζω εἰς μετανοίαν—into repentance (Matt. 3:11). He does not merely preach a βάπτισμα, but a βάπτισμα μετανοίας—of repentance (Mark 1:4; Luke 3:3). The nature of his baptism is βάπτισμα μετανοίας εἰς ἄφεσιν ἁμαρτιῶν—baptism of repentance into the remission of sins (Mark 1:4; Luke 3:3).
John does not merely say Ἐγω βαπτίζω, but Ἐγω βαπτίζω εἰς μετανοίαν—into repentance (Matt. 3:11). He does not merely preach a βάπτισμα, but a βάπτισμα μετανοίας—of repentance (Mark 1:4; Luke 3:3). The nature of his baptism is βάπτισμα μετανοίας εἰς ἄφεσιν ἁμαρτιῶν—baptism of repentance into the remission of sins (Mark 1:4; Luke 3:3).
"And [Paul] said, 'Into what then were you baptized?' And they said, 'Into John's baptism.'" Acts 19:3Both the Pharisees and the Apostle Paul asked the same essential question, though not identical in every respect. Both questions reveal variety in the nature of baptisms. The answer "We were baptized into John's baptism" gave Paul all the information he desired. Likewise, John's answer gave the Pharisees all the information they sought.
Just as the Israelites under Moses' leadership had to pass through the Red Sea at the exodus, and just as the second generation of Israelites under Joshua's leadership had to do the same thing at the Jordan River, so now true Israelites must identify with the water and their prophetic leader in order to begin experiencing true restoration. In 1 Corinthians 10:1-2, the passing through the Red Sea is described as a "baptism." So, too, could the passing through the Jordan River. These "baptisms" merely identified the Israelites with their prophetic leaders. So, too, with John's baptism.
The Baptism which John preached and the Baptism which John administered were one and the same baptism. John preached the imperative necessity for a thorough change in the condition of the soul manifested by godly repentance and issuing in the full remission of sin through "the Lamb of God that taketh away the sin of the world;" which changed condition of the soul was the work of the Holy Ghost. This baptism of the soul which was set forth by words in the preaching was identically the same baptism which was set forth by water in the rite. The purification of the soul was always effected, as a fact, by the Holy Ghost; and the purification of the soul was always exhibited, as a necessity, by the pure symbol. The agencies differed infinitely; the baptism was one absolutely—effected in the one case, symbolized in the other.
Matthew's "Repent!" and Mark's and Luke's "Baptism of repentance into the remission of sins," and John's "Behold! the Lamb of God that taketh away the sin of the world," have all alike the same amount of water in them; that is to say, just as much as may be found in the burned out craters of the moon. The verb βαπτίζω and the noun βάπτισμα, as used in the history of John's baptism, have no more to do with the quantity or the manner of using the water employed in his symbol rite, than has the multiplication table to do with the amount or the manner of using Rothschild's wealth. Let these words mean what they may, they have no more control, in the relations in which they stand, over the use of the water, than a sleeping infant has over the earth's diurnal revolution.1
The word βαπτίζω, as used in Scripture, has no more control over or connection with the manner of using this water, than a broken arm has control over or connection with the movement of the solar system.2
βαπτιστὴς has nothing to do with water in any form or measure. It carries no water with it. John ὁ βαπτιστὴς is and can only be, John the Purifier. Ιωάννης ὁ βαπτιστὴς = John the Purifier.
1 James W. Dale, Johannic Baptism, p.407.
2 Ibid, p.417.