Many current writers can read and write in the Koine Greek that the Scriptures were written in, dedicate their life to the study of the Scriptures, and pastor a chuch. The only thing difference is that they live today, not back in the time of Chrysostom. A close friend of mine, when I asked to see his bible, handed it to me and I saw that there wasn't a single English word in it! Yet as he read from it he translated it into English.
The difference is that Peter spoke of Christ being of divine nature in a way that was unique to Christ, while Martha and Nathaniel did not indicate the Jesus was a son of God like no other. There is little in the actual text that says so, but we trust that Christ detected the conviction in Peter that wasn't with Martha (who was, St. John writes, confused) or with Nathaniel (who was startled by Jesus's clairvoyance).
You're correct in that there is little if anything in the text that warrents what you just said above.
That is critical - they have not made that culture and mentality their own. I, of course, also read modern scholars of the scripture, but I will take the patristic interpretation over theirs any time.