This statement has faulty reasoning. The so-called need to see extra-biblical references is an avoidance mechanism. Here’s why.
The original writings (the gospels) were “outside the bible” when they were written. The canonical writings were not organized as such until hundreds of years later. To anyone of the first few centuries, the writings about Jesus were independent documents circulated by individuals. The New Testament is simply a collection / library of works that were gathered together later because they were determined to be trustworthy. So until they were gathered together in a formal format, all of them were “outside the bible.”
1. Supposedly there needs to be [trustworthy writings] about Jesus that are [not in the bible] to trust Jesus’ validity.
2. At a point in previous history a council gathered up all the [trustworthy writings] about Jesus and bound them in a work called the bible.
3. Therefore, there are no more [trustworthy writings] about Jesus that are outside the bible.
It’s self defeating reasoning. It’s smoke and mirrors. It’s just an avoidance mechanism. It’s a convenient way to avoid the story of Christ. If all of the trustworthy writings are gathered together, into the bible, then of course you will not find any trustworthy references to Jesus in other outside sources.
There is a mountain of evidence. The Christ Mythologist, conveniently sweeps all the biblical references about Jesus into the “biased” category, and all of the non-biblical references into the “plagiarized” category. So if you remove all of those very substantial writings about Jesus, then of course there is nothing left. What a straw man. It sounds like an intelligent argument until you consider what is actually going on.