towerwatchman,
I can provide the chiasm, but I would first like people to investigate for themselves because activity is the best way to learn and for things to stick. So let's just wait a while and see what people discover is the focus of the chiasm and hence its purpose. At the same time, it provides an understanding of what the Johannine Community intended with that opening as well as providing a mechanism for understanding the message of the remainder of their Gospel.
The Prologue was written well after that community had developed their High Christology, much later than other parts of the Gospel. The aporia are used by scholars (and I am most certainly not one!) to distinguish the individual elements of the Gospel and their likely location in the evolution of its writing.
In my understanding, the Johannine Community was directly addressing its own community members and referencing their experiences at the hand of the synagogue community. As for 1 John, rather than seeing it as addressing Gnosticism, I understand that it was addressing those who had been members of the Johannine Community but had formed their own breakaway schism.
I agree that these Johannine writings concern that Community's views on Christ (and hence on their soteriology). The writers (and I include Paul in this regard) were not writing theology. They were addressing their immediate and local concerns.
Doug