The first Gospels may have been written 40 or more years after Christ -
how could they get the facts?
Some of the writers probably were eyewitnesses. Even if not, Pope
Clement I, in his letter to Corinth of c 95 AD says Peter & Paul were
of his own generation. They probably died c 67. So he must have heard
them. Also we have Ignatius of Antioch who came from the see where
Peter had worked not long before; and Quadratus, saying some in his day
were still alive who had been cured by Christ or raised by Him. Even if
not in 123, this covers easily 80-90 AD when many say Mt. & Lk were
written.