Well when Judas died, they replaced him with Mathias, “and let another take his place”. They did not leave his chair empty.
Apostolic succession is the line of bishops stretching back to the apostles. All over the world, all Catholic bishops are part of a lineage that goes back to the time of the apostles, something that is impossible in other denominations (most of which do not even claim to have bishops).
The role of apostolic succession in preserving true doctrine is illustrated in the Bible. To make sure that the apostles’ teachings would be passed down after the deaths of the apostles, Paul told Timothy, “[W]hat you have heard from me before many witnesses entrust to faithful men who will be able to teach others also” (2 Tim. 2:2). In this passage he refers to the first three generations of apostolic succession—his own generation, Timothy’s generation, and the generation Timothy will teach.
The Church Fathers, who were links in that chain of succession, regularly appealed to apostolic succession as a test for whether Catholics or heretics had correct doctrine. This was necessary because heretics simply put their own interpretations, even bizarre ones, on Scripture. Clearly, something other than Scripture had to be used as an ultimate test of doctrine in these cases.
For the early Fathers, “the identity of the oral tradition with the original revelation is guaranteed by the unbroken succession of bishops in the great sees going back lineally to the apostles. . . . [A]n additional safeguard is supplied by the Holy Spirit, for the message committed was to the Church, and the Church is the home of the Spirit. Indeed, the Church’s bishops are . . . Spirit-endowed men who have been vouchsafed ‘an infallible charism of truth’” (Early Christian Doctrines, 37).
Besides, not everything is in Scripture, the doctrine of the Trinity (for example) was developed by the Church.
It was the Church who established the Canon of Scripture in 398 AD, by this time the Church was on it’s 15th Pope.
Remember that Jesus commanded no one to write the Bible, the Church did this with the help of the Holy Spirit of course.
Many people from different faiths tell me that their church is the same as the original Church. But when they read the letters from the Church Fathers, their beliefs do not match.
Eusebius of Caesarea
“At that time [A.D. 150] there flourished in the Church Hegesippus, whom we know from what has gone before, and Dionysius, bishop of Corinth, and another bishop, Pinytus of Crete, and besides these, Philip, and Apollinarius, and Melito, and Musanus, and Modestus, and, finally, Irenaeus. From them has come down to us in writing, the sound and orthodox faith received from tradition” (Church History 4:21).
Paul told Timothy, “[W]hat you have heard from me before many witnesses entrust to faithful men who will be able to teach others also” (2 Tim. 2:2).
That's it!? You found a verse about replacing Judas and a verse about sharing the gospel. Ya kind of missed the mark didn't you. All the rest is babble. By the way a Bishop is an Elder. You have 1 billion people that believe in the authority of the pope but you have no scripture at all which is similar to Marian doctrine. I imagine it's easy for you to see why anyone who believes that all doctrine must come from the bible would not ever become a Catholic.