In the introduction to Robert L. Webb's John the Baptizer and Prophet: A Socio-historical Study (1991; rep., Eugene: Wipf and Stock, 2006), 19, he writes:
While this isn't completely true since scholars of the Mandaeans must discuss how this religion has venerated John to this day it is true of scholarship on Judaism and Christianity. The early Jesus-movement felt obligated to explain how John's preaching related to their preaching and activity. Obviously, John was a big enough deal in that day that some endorsement of Jesus from John was necessary for the Evangelists (John also appears in the Gospels of Thomas, of the Ebionites, of the Nazarenes, and in the Protoevangelium of James, but all of these may rely on the Synoptics and the Gospel of John for their information). Yet, as history would have it, John's memory is preserved primarily because of the Jesus-movement, even as the Jesus-movement demoted John in the ears of their hearers.
I say that to say this: I know that any discussion of John is connected to Christianity somehow, unless someone brackets Josephus' mentioning of John. But in May I will be teaching at University Presbyterian Church on John the Baptist for four weeks for an hour each Sunday and it is possible that I may do it again for the Sol Center this fall for two hours a week over four weeks. While I will be talking about John primarily as he is depicted in the aforementioned gospels and by Josephus I do want to say something about John's value outside of Christianity's "forerunner" motif. Again, I know this is what brought John to us, but I'm convinced that in his own day John was loved or hated in his own right and that he has something to offer as an example for modern Christians, Jews, Muslims, Mandaeans, etc. In my opinion, John is just as much the inheritance of modern Judaism as he is modern Christianity, he is as valuable to modern Muslims as he is to modern Mandaeans, but how to discuss this?
In part, I think I will approach this from the angle of the history of scholarship. Just as historical Jesus studies may say more about the scholarship of an era than Jesus of Nazareth, so historical Jesus studies that mention John, or the handful of historical John projects, may explain what John has "meant" to us over the last few hundred years as much as or more than what he meant to his contemporaries. Related, I may begin researching how John is depicted in Jesus films and whether there are any trends to be observed. The other angle will be John's depiction across world religions. I think I know how to talk about John as he relates to Judaism since, well, John wasn't a "Christian," but a Jewish prophet, but I am not familiar enough with contemporary Judaism to know if he is ever mentioned in those circles. Furthermore, what do Muslims say about John? If anyone out there has anything valuable to share, I'm all ears. Of course, I'll be doing my own preparation, but it would be nice to have some extra help from those who know more about John's reception in other religious communities.