Note 5: "According to conventional accounts of the chronology of Yehoshua ben Perahya, he lived well before Jesus and could not have come in contact with him. The rabbis here reveal either ignorance of Jesus' chronology or a lack of concern for historical accuracy. It is conceivable, although unlikely, that the present story has in mind a Jesus other than the founder of the Christian faith."
There is a crucial point that Kalmin misses. As is well known, The Jewish chronology differs from the general chronology by some 150 years. What is particularly interesting here is that Jesus would fit quite perfectly into Yehosua Ben Perachya's times according to chronology of the Rabbis. Assuming the general chronoly correct (which seems likely) one would have to say that the Amoraim had a tradition that Yeshu was a student of an important Rabbi of his time but following their own chronology they assumed it to be Yehoshua ben Perachya (who was the only well-know Rabbi who had run off to Egypt. וצ"ע ויש להאריך ואכ"מ
Kalmin consistently refers to minim and Christians, without attempting to define minnim.
(He provides the following sources -25 On the question of the identity of these minim, see Hirshman, "Midrash Qohelet Rabbah," 2. 61; Burton L. Visotzky, "Overturning the Lamp," JJS 38 (1987) 76-77; and Stuart S. Miller, "The Minim of Sepphoris Reconsidered," HTR 86 (1993) 384-85 n. 31. - The only one I have at the moment is the last and that one is to specific to be useful).
I would imagine that the other "non-jewish bible readers" were some form of gnosticism. (R' Yosef Zecharya Stern (Maamer Al Tahluchei Aggados - possibly quoting someone else) suggests that the etymology of the word min is related to the founder of mancheism - Manos). The discussions in the Talmud trying to refute the doctrine of dualism (Berachot - Yotzer Ohr U' Borei Choshech, Acc. to Shadal the Ohr L' Arbaah Assar of the first Mishna in Pesachim was because of a desire to avoid referring to the dark (D' Lo K'Hagemara and it seems unlikely anyway), there is also a discussion somewhere abou Hormuz and Ahormuz but I can't find it a at the moment.)
If one assumes the tale of Yeshu and Yehoshua ben Percahya is a historical then it was the Rabbis explanation for the excessive emphasis on Repentance in the NT. If it is historical then this is what caused that doctrine.