They validate the existence of Jesus because there is corroborating evidence of his existence and crucifixion in Roman documents.

They DO NOT validate the inerrancy of the Bible dogma, because you can't.

There's proof it's been altered over the centuries. It's been reinterpreted many times. It's also a collection of Holy documents in which other equally Holy documents were purposefully excluded for very specific reasons.

Here's a reference for you.

The Rise of Christianity by WHC Frend.