i have been meaning to ask you the very same question, bb. mark admits that the Gospels were written anonymously and that they were assigned authorship by the Church according to tradition (legendary belief) towards the end of the second century. Until then, no one quotes from the Gospels and says "according to Matthew, etc."
Mark accepts that his Church believes they were written by the authors whose names we are familiar with. And you accept them based on what, since you reject the authority or the tradition of the Church?
When you say "investigate the truth," what truth are investigating? That no witnesses were ever named, and that even the authors who wrote about the unnamed witnesses are not named except according to the legend and tradition believed by the Church you reject?
Glad you asked. I was doing a little research last night and I discovered quite a bit more concerning your "no eyewitnesses". First of all, many names are given in the scriptures and we know from history and "traditions" - see we aren't scared of that word - that they were real people. Remember, the books were written while many of those same eyewitnesses were still living and could have, would have, disputed the claims were they untrue.
Let's just look at the first few books of the NT (as far as I got last night). Although specific names were not given every time, and I think they weren't simply because it was not the point to glorify them, many of the people back then knew exactly who was being spoken of and we can know from the traditional works what some of those people went on to accomplish. BTW....what good would it do to give the name of the lepers healed by Jesus, we would not know who they were today, nor really care, would you?
From Matthew first few chapters, the people spoken of were:
Mary, Joseph, the Magi, the people who lived in Nazareth, John the Baptist, the people who lived in Capernium area of Zebulon and Naphtali, Simon Peter, Andrew his brother, James and John and their Dad, Zebedee, people in Galilee and Decapolis, Jerusalem, Judea, across the Jordan, all the crowd on the hillside during the sermons, the man healed of leprosy, the Capernium centurian and his servant who was healed, Peter's mother-in-law.
I could go on, but I hope you see my point. Read for yourself the accounts of those healed, who believed, who spoke both for and against the teachings and actions of Jesus and his disciples. Their voices cry out to me and I find it hard to believe they were all some figment of someone's imagination.