Dear HisWill777,
First of all, I love your “777”!

The perfection of God overcomes the imperfection of man.
To answer your question, it’s important to know some about the nature of Scripture. When the New Testament’s first books were being written, Christianity had already existed for about 20 years. During those 20 years, Christianity was passed on exclusively through preaching, through the oral passing on of Jesus’ revelations from one mouth to another. As Acts 2:42 says, “they devoted themselves to the apostles’ teaching.” During that period, when people had a question, they didn’t look to the Bible for an answer. They asked the apostles their question and the apostles would tell them what Jesus told them.
When the Bible was originally written, it wasn’t intended to be a doctrinal dissertation or a list of all the truths of the Christian faith. You have a couple epistles to the Corinthians, focused on their specific needs, a long and very deep epistle to the Romans discussing the faith, some short epistles to other churches or individuals, and some long. None of them says in the introduction that it is going to present a compilation of all the truths of Christianity, though. That wasn’t the writers’ purpose. Their purpose was to meet the needs or situations of the churches or people they were writing to. In fact, certain parts of the Bible indicate that the authors didn’t even know they were writing God’s inspired Word. Maybe the Apostle John did when writing the Apocalypse, but Paul doesn’t seem to have known when he wrote in 1 Corinthians 7:12, “To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her . . .” He doesn’t seem to have known that the Lord was inspiring his words, for he says here that they are his words not the Lord’s. Is this the only uninspired passage in the Bible? No. Paul simply didn’t know how remarkably God was using him at the time.
… This teaching was transmitted in oral tradition which was considered infallible, protected by God from error just as the Bible is protected from error. The Bible wasn’t written to tell every doctrine of Christian truth and it wasn’t needed to tell every doctrine of Christian truth (though IMO, it does that too, because God is so glorious). Therefore one wouldn’t have needed to see the “outside of the Church there is no salvation” dogma explicitly laid out in the Bible. The Christians of the period had the teachings of the apostles, Tradition, the same guide Christians used in the first 20 years of Christian history. The Bible was added to the teachings of the apostles, presenting the teachings of the apostles that were originally provided through oral transmission, and much (though not all) of its New Testament is written by apostles.
Now, as far as this particular issue we’re discussing goes, you need to take into account what the Church meant at that time. At the time of the apostles, the Church was both visible and invisible, mystical and corporal. It had a human structure with elders, presbyters and overseers (or bishops) who had authority over the members of the Body, the Church. As Paul wrote in Hebrews 13:17, “Obey your leaders and submit to them, for they keep watch over your souls as those who will give an account.” There are many other passages referring to the authority of the Church leaders. I won’t take the time to present all of them here.
In this time period, the dawn of Christianity, there was only one Church. All Christians were united in the apostolic teaching at that time without any division. If anyone believed in Jesus, they entered the Church. So when Peter insists to the crowds in the Book of Acts that everyone must believe in the Name of Jesus to be saved, it is assumed that they will enter the Church of Jesus, which is the Salvific Body of Jesus. There was no need for the Bible’s writers to say, “you must enter this Church of Jesus to be saved and no other,” because there was no other. But that teaching was one of the original beliefs of the Church from the very beginning, as many quotes from the Early Church Fathers prove. They believed that this was part of the apostles’ teaching, and this doctrine is actually very glorious and beautiful. I want to show you that in my next post.