The Gospels have the pattern of names we would expect them to have if they are reporting what real people said and did.He also looks at the geography and botany in the Gospels.
The pattern would be too complex for an ancient forger to produce.
Can't prove everything to be historical
But if the Gospels result from conspiracy or incompetence this is not what you would expect
If the Gospels were produced on basis of stories several steps removed from eyewitnesses this is not what you expect