First, it tacitly assumes the very thing that it is supposed to be proving. Both Catholics and Protestants take the Scriptures as reliable sources of information about God even if any given individuals in either camp cannot produce external supports for it. Protestants at least admit that this is what they are doing. Catholics, on the other hand (particularly the apologists), propose to treat Scripture "only as a historical document", which they then use to build up the authority of their Church. But in so doing, they ignore the fact that they are assuming that they "know" what books constitute "Scripture"--the very thing they deny that can be done apart from their Church!
But the Catholic apologist is not, at this point, accepting the evidence in Scripture because it is Scripture. Rather, he is looking at each book in Scripture as purely an historical document. Before we ask the question "is this divinely inspired," we merely ask is this accurate? At this point we are only treating it as we would the letters of Pliny or Josephus' histories. From the viewpoint of an historian, what do they tell us of the church?
Even without accepting them as divinely inspired and thus infallible we can see a church established by Jesus with an authority given to the Apostles who latter associated other men in its leadership. We can also see that they preached that Jesus was the Son of God who rose from the dead which they claimed to have witnessed. We also know that they gave their lives for their preaching. We can also compare what they proclaimed with what was written in the Old Testament. All this can be established before declaring that their writings are divinely inspired and thus infallible.
It is from this that we can accept the truthfulness of their testimony. Their testimony being truthful then they did indeed witness Jesus rising from the dead. From this we can have faith that Jesus is the Son of God. If he is the Son of God then the church has the divine authority that he gave to it. And then it is by this divine authority that we can accept what the church proclaims to be Sacred Scripture. Nothing in this is begging the question as the author claims.
Second, the claim that the identity and supreme authority of the Roman Catholic institutional Church can be established to be true solely by the use of non-inspired historical writings neglects to factor into its equation the fact that historical arguments are by their nature fallible, since they are constructed by fallible people who can never know all the facts and their inter-relationships with perfect clarity.
But no one has ever claimed that knowledge through historical documents is infallible, only that there is a high degree of certainty. This it true for all historical knowledge, including our knowledge that the present text of Scripture matches the originals. It is with this high degree of certainty that we can accept the present Catholic Church as that established by Jesus Christ.
Finally, the author does not address how, without an authoritative church, a Protestant can know what is the true canon of Scripture. His only response can be "I know it is true because I can feel it in my heart." Thus the Protestant's reliance on sola scriptura is reduced to sola opinione mea.
Where oh where have we heard that before?
Sure it is begging the question! The Apostles were given authority in word and in power by Jesus Christ. Paul declared to the Thessalonians:
And to the Corinthians, he said:
The writings handed down to the churches BY the Apostles were authoritative because they were from GOD. The believers were remanded to OBEY the instructions given to them in writing (see 2 Thess. 3:14; Romans 16:17; Colossians 4:16; 2 Thess. 3:6; Titus 2:8; 2 John 1:10). They did not, however, have to first wait around for their church "leaders" to decide whether or not to accept the Apostolic writings as from God before they obeyed. This is why it is error to presume the church, Catholic or otherwise, had God-given authority to define Divinely-inspired writings. They received them and obeyed because they knew from whom they received them. Just as the Jewish people were held to obey all that the Lord gave to them through Moses and the prophets or suffer His judgment.
This is why we know that Holy Scripture IS the objective authority for our faith - NOT the "church". The church - as the body of Christ - is to be in submission to God's sacred word. The way we can distinguish a genuine church from one that is not is from Scripture. Scripture tells us what a true church of Christ teaches, how it behaves, what it is commissioned to do, what results are expected as well as what Gospel it preaches. Scripture is the standard by which truth claims are measured - and that was how the early church leaders saw it. Some went so far as to say their words should be disregarded if what they taught could not be shown from Holy Scripture. That is a far cry from what the Roman Catholic church teaches today. According to Rome, the fact that they SAY something is true, is all the authority anyone needs. Truth becomes whatever they say it is rather than what God has said (see Rome's New and Novel Concept of Tradition Living Tradition (Viva Voce - Whatever We Say)). This was NOT how the early church behaved.