John the Baptist and Baptism: 1:25ff 3:23 10:40
The author of the FG assumed some kind of knowledge of the general story about Jesus. This can be seen in a few places. In 1:40, Andrew is introduced to the reader as “Simon Peter’s brother.” However, Simon Peter has not yet been introduced; that occurs in the following verse (1:41). This does not necessitate a claim to Johannine literary dependence upon the Synoptics. Other examples are found at 3:24 (an analeptic reference to John the Baptist being thrown into prison); and 11:1–2 (an analeptic reference to Mary anointing Jesus’ feet). Therefore, familiarity with the general story about Jesus is assumed. It should also be mentioned that John the Baptist is always referred to as “John,” without the additional “the Baptist.” While this is frequently used to support evidence of apostolic authorship, it also demonstrates that the audience probably was already familiar with John (the Baptist’s) ministry.
If the above is true, and the emphasis of John’s ministry, as confirmed in the Synoptics, was repentance and baptism, then it may be the case that the author of the FG did not find it necessary to repeat much about John since knowledge about him was already assumed.
The words for “baptism” occur frequently with words for repentance in the NT (for example, see Matt 3:6–16; Mark 1:4–9; Luke 3:7–21; Acts 2:38–41; 8:12–38; 11:16; 19:3–5). In the FG, baptizo occurs thirteen times. The relationship of baptism to repentance may have been strong enough for the author of the FG to not find it necessary to make this link explicit.
Another connection, which could be made between John the Baptist and repentance, is the mention of “purification” in 3:25. While purification may refer to John’s baptism, Carson (more perceptively) connects this “purification” with the same word in 2:6 and thus Jewish purification rites are in mind. While more will be said about 2:6 later, Morris’ conclusion regarding this dispute is surely astute: “This verse is compressed to the point of obscurity.”
While the former text may allude (from a very distant perspective) to repentance, it surely is not strong enough to connect them tightly. The latter text does not meet the standards. Therefore, neither text adequately contain the concept of repentance.