I continued the conversation and another Muslim said this. How do I answer? It is long.
This is how the discussion went:
I said that Christians don’t have an Isnad (chain of transmission).
LUX IN TENEBRIS:
“Now Christians do have a detailed isnad, but not of what you would expect. We have a detailed isnad for Apostolic succession, i.e. the Bishops that succeeded the Apostles. This isnad was used to combat early gnostic heresies, which claimed a secret knowledge from the apostles. The importance is that it does show a connnection to the past. Christ promised He would be with His church till the end of time, and that He would send the Holy Spirit to guide and protect her, so we know the Church that is built on the Apostles is free from error, and this is by Divine protection.”
My response:
"There exists confusion regarding the chronological order of the Popes and their actual indentities.
All the ancient records of the Roman bishops which have been handed down to us by St. Irenaeus, Julius Africanus, St. Hippolytus, Eusebius, also the Liberian catalogue of 354, place the name of Linus directly after that of the Prince of the Apostles, St. Peter. These records are traced back to a list of the Roman bishops which existed in the time of Pope Eleutherus (about 174-189), when Irenaeus wrote his book “Adversus haereses”. As opposed to this testimony, we cannot accept as more reliable Tertullian’s assertion, which unquestionably places St. Clement (De praescriptione, xxii) after the Apostle Peter, as was also done later by other Latin scholars (Jerome, Illustrious Men 15). The Roman list in Irenaeus has undoubtedly greater claims to historical authority.
**The second successor of St. Peter. Whether he was the same as Cletus, who is also called Anencletus as well as Anacletus, has been the subject of endless discussion. Irenaeus, Eusebius, Augustine, Optatus, use both names indifferently as of one person. Tertullian omits him altogether. To add to the confusion, the order is different. Thus Irenaeus has Linus, Anacletus, Clement; whereas Augustine and Optatus put Clement before Anacletus. On the other hand, the “Catalogus Liberianus”, the “Carmen contra Marcionem” and the “Liber Pontificalis”, all most respectable for their antiquity, make Cletus and Anacletus distinct from each other; while the “Catalogus Felicianus” even sets the latter down as a Greek, the former as a Roman.
According to Tertullian, writing c. 199, the Roman Church claimed that Clement was ordained by St. Peter (De Praescript., xxxii), and St. Jerome tells us that in his time “most of the Latins” held that Clement was the immediate successor of the Apostle (Illustrious Men 15). St. Jerome himself in several other places follows this opinion, but here he correctly states that Clement was the fourth pope. The early evidence shows great variety. **
This information is from the Catholic Encyclopedia. If there is one word that can summarize this Apostolic succession, it is - confusion. For any Muslim or anybody who really isn’t familiar with this information, this talk is regarding the first Popes that came after Peter the Apostle who is said to have been the disciple of Jesus (peace be upon him). It is indeed a sad state of affairs when the chronological order and even identities are put into question.
I’ll give an analogy from the Islamic succession of the Khilafah. It indeed would be a sad state of affairs if Muslims were not certain who succeeded the Prophet Muhammad (peace and blessings of God be upon). What would it sound like to you if people were saying that Abu Bakr was the first, others were saying Umar was actually the first and then others that Uthman was the first. And to make matters even more laughable people wouldn’t even be sure regarding the identity of Uthman, some would be saying that he was actually Ali and some saying that he was Arab and others that he was actually Persian. And to top it off, people would have varying lists with some having Umar first followed by Abu Bakr and others with Uthman followed by Umar. Obviously this analogy is not really all that great because everybody unanimously agrees that Abu Bakr was the Caliph after the Prophet Muhammad (peace and blessings of God be upon him), followed by Umar, followed by Uthman, followed by Ali and their biographies are well known(may God be pleased with them all), but it does show how obviously ridiculous it is when the order of Popes and their identities are disputed . And Lux, don’t try to pull out the Shia card and say that there is confusion since their error deals with theology and who ought to have been Caliph, not with actual history.
So you see, this is why I really don’t give Apostolic Succession much credit because obviously there exists a great amount of confusion."
The same can repeated for all the Gospels. They cannot be traced back to their authors.
We consider the mainstream Gospels in the same way that modern Christians consider Apocrypha, i.e. they are not valid works, they were not written by the people whom they are claimed to be written by, they cannot be traced back to the original authors.