We have no other evidence other than "eyewitness". We can only know what our senses tell us or what others senses tell them. There is no such thing as evidence that is not "eyewitness".
Biblical evidence required to accept a verdict in law or to accept someone's testimony as true is much higher than our own courts of law. There must be at least three witnesses and self testimony is invalid. As you read about each biblical miracle you will note the presence of multiple witnesses. The authors knew their audience would not accept anything less.
But what we have is the author, which is one source.
I really don't have any interest in arguing about religion. My interest is in what's taught in science class, and science is skeptical.
If an established principal or formula ceases to provide reliable answers, the formula is questioned. Established principles are continually being revised and updated. There are current tests being proposed for Einstein's general relativity, even though every experiment so far has confirmed it beyond ten decimal places.
There are always gunslingers who hope to make a reputation by finding a discrepancy in the eleventh.