For starters, I’d ask to see proof positive for this blanket statement.
After that, I guess my answer would depend on whether the person making the comment is Christian or not… but either way, the following from Proving Inspiration might help:
An Accurate Text
Sir Frederic Kenyon, in The Story of the Bible, notes that “For all the works of classical antiquity we have to depend on manuscripts written long after their original composition. The author who is the best case in this respect is Virgil, yet the earliest manuscript of Virgil that we now possess was written some 350 years after his death. For all other classical writers, the interval between the date of the author and the earliest extant manuscript of his works is much greater. For Livy it is about 500 years, for Horace 900, for most of Plato 1,300, for Euripides 1,600.” Yet no one seriously disputes that we have accurate copies of the works of these writers. However, in the case of the New Testament we have parts of manuscripts dating from the first and early second centuries, only a few decades after the works were penned.
Not only are the biblical manuscripts that we have older than those for classical authors, we have in sheer numbers far more manuscripts from which to work. Some are whole books of the Bible, others fragments of just a few words, but there are literally thousands of manuscripts in Hebrew, Greek, Latin, Coptic, Syriac, and other languages. This means that we can be sure we have an authentic text, and we can work from it with confidence.
The Bible as Historical Truth
Next we take a look at what the Bible, considered merely as a history, tells us, focusing particularly on the New Testament, and more specifically the Gospels. We examine the account contained therein of Jesus’ life, death, and resurrection.
Using what is in the Gospels themselves and what we find in extra-biblical writings from the early centuries, together with what we know of human nature (and what we can otherwise, from natural reason alone, know of divine nature), we conclude that either Jesus was just what he claimed to be—God—or he was crazy. (The one thing we know he could not have been was merely a good man who was not God, since no merely good man would make the claims he made.)
We are able to eliminate the possibility of his being a madman not just from what he said but from what his followers did after his death. Many critics of the Gospel accounts of the resurrection claim that Christ did not truly rise, that his followers took his body from the tomb and then proclaimed him risen from the dead. According to these critics, the resurrection was nothing more than a hoax. Devising a hoax to glorify a friend and mentor is one thing, but you do not find people dying for a hoax, at least not one from which they derive no benefit. Certainly if Christ had not risen his disciples would not have died horrible deaths affirming the reality and truth of the resurrection. The result of this line of reasoning is that we must conclude that Jesus indeed rose from the dead. Consequently, his claims concerning himself—including his claim to be God—have credibility. He meant what he said and did what he said he would do.
Further, Christ said he would found a Church. Both the Bible (still taken as *merely a historical *book, not yet as an inspired one) and other ancient works attest to the fact that Christ established a Church with the rudiments of what we see in the Catholic Church today—papacy, hierarchy, priesthood, sacraments, and teaching authority.
We have thus taken the material and purely historically concluded that Jesus founded the Catholic Church. Because of his Resurrection we have reason to take seriously his claims concerning the Church, including its authority to teach in his name.