I've been following the discussion about methodology etc., but the fiddly bits of historical epistomology are getting a little dry for an amateur. So I'd like to go back to the basics as Neil suggested :
Let's go back to these very foundations - who can we say existed with a high level of confidence ?
(I've been struggling with wishy-washy terms like 'fairly certain' or 'almost certain', or 'quite likely etc., so I've decided to add rough estimates of probability of existence as percentages. Never 100% of course.)
Note to Bernard et al - I certainly am NOT claiming that ONLY these persons existed, just that they have fairly solid evidence. We can build on this foundation with others less likely.
I use the term 'primary evidence' to refer to contemporary evidence - if it's not contemporary then it's not primary.
The goal here is to see if we can reach a consensus on the foundational characters, and perhaps use it to discuss those less certain.
Considering the evidence - the early Christian writings and the early Greek, Jewish and Roman writings - here are the persons with solid foundations that I think we could all agree to with a reasonably high level of confidence :
Paul wrote letters mid 1st century - from primary evidence, although corrupt. Various cities around the Eastern Mediterranean.
Paul knew someone in Jerusalem named James, also called the Lord's Brother (confirmed by secondary evidence.)
Paul wrote of someone in Jerusalem called Peter, otherwise unknown.
Probably wrote a gospel in Sinope in early-mid 2nd century. No primary evidence, but much secondary.
Wrote the DiaTessaron and more in Syria mid 2nd century. Primary evidence in his Address.
Justin Martyr. 95%
Wrote about several 'memoirs' or gospels mid 2nd century, in Rome. Primary evidence of his own writing.
Collected, named, and numbered four Gospels in Lyons in late 2nd century. Primary evidence from his own writing.
Somewhere in there are our old friends Athenagoras, M. Felix, and Theophilus, who left primary evidence of themselves at least. Followed by much primary evidence from Clement of Alexandria, Tertullian, Origen and Hippolytus around the turn into the third century, and more following.
Otherwise, I don't think anyone else in the first two centuries has a solid existence from primary evidence. Marcion is the furthest into secondary evidence I haved dared to go, and even he is not that certain.
I look forward to comments