My point is that we are quite unlikely to find hard proof as such. We don't have objective reports and archeology is limited in what it has the capacity to prove.
I gave the "current" scholarship on Josephus including what was forged and not - that can change too.
We don't even really know much at all about what the Pharisee, Saducees, etc. taught. We don't know that Qumran was Essene, who wrote the Dead Sea Scrolls, etc. etc.
I agree with your conclusion based on "all surviving copies of Matthew 28:19," however this is not hard proof.
This is all assuming some common definition of hard, objective "proof," however considering all possible evidence, I believe that by most definitions, it is not possible for the time period and the type of events we are looking at.
thanks for your reply.
There is a Latin saying , with a grain of salt. That's how we should take ancient evidence. One can be certain in his beliefs, but one cannot sue his beliefs as proof of their veracity. And neither can we use the surviving documents. That's why the Church in her blessed wisdom calls it a faith, trust, hope, and not 'knowledge'.
As the eulogist said at Patriarch Alexi's funeral liturgy "We hope God will accept his soul." In other words, only God knows; we can only hope. Arrogance has no place in the catholic faith.