I think the way to respond to this is that your friend’s is a careless statement. My support is from Keating’s book Catholicism and Fundamentalism where he says of the Sacred Scripture
“…we are able to conclude that we have a text the accuracy of which is more certain than the accuracy of any other ancient work.”
He explains that though no one disputes we have accurate copies of the works of Virgil, Livy, Horace, Plato, Euripides—yet the earliest manuscripts that we now possess were written from 350–1,600 years after the deaths of these authors.
Not only are the biblical manuscripts we have older than those for classical authors, we have in absolute numbers far more manuscripts to work from. Some are whole books of the Bible, others fragments of just a few words, but there are thousands of manuscripts in Hebrew, Greek, Latin, Coptic, Syriac, and other languages. What this means is that we can be sure we have an accurate text, and we can work from it in confidence."
I didn’t see any references in the pages to the written foundations of eastern religions like Buddhism, so don’t know if Buddhists say they have writings contemporaneous with the Buddha. Don’t think so.
Hope this helps.