dear designs...
would it be correct to say that there is no proof that isaiah was getting messages from God, transmitting them accurately or that he even existed, there is no collaborating contemporaneous witness to his person. You believe he existed and that he transmitted God's message based on faith. (Even as an atheist!!)
the NT gospels are all collaborating the events leading up to the crucifixion of Jesus and witnesses collaborate each other.
if christians believe isaiah was a prophet of God and he accurately transmitted God's message then why on earth WOULDN'T we believe the gospel testimony?
think about this for a few minutes...from what quarter is OT credibility coming from? Is it islam(who's "prophet" found need to do a re-write to accommodate his new religion) or is it from any other major religion? Who besides the jewish people believes isaiah and supports use of the OT without "evidence" for its veracity? It is christians...it is christians BECAUSE we have a shared faith in the same God. If that wasn't the case then what was the real motivation for gentiles to believe in sin and atonement OR a Messiah. God called us to believe in Him too despite animosity from jewish leaders and religious persecution on the part of roman authorities.
You can think and say whatever you want about what happened back then but it doesn't jive with the "evidence" or reality of Jesus' church.
love michelle