Without the Bible, you would learn about Christ the same way as most Christians did in the beginning - they heard the gospel from the Church and her missionaries. Most of the early converts would have been illiterate and wouldn't have read the Bible at all.
Perhaps.
But the Jews would have heard their Scriptures read to them, and both Peter and Paul preached from the Jewish Scriptures, and quoted them to back up their preaching of the gospel. The Berean Jews were literate in the Hebrew Scriptures and possibly the Septuagint, and they were able to search the Scriptures to see if Paul was preaching the truth.
Also, the resurrected Jesus was able to show the two disciples at Emmaeus through the Scriptures all the references to Himself. Also, because Alexander the Great introduced Koine Greek, a much simpler version of classical Greek, all throughout the lands which he conquered, so many would be able to read and write it.
The four Gospel writers could read and write, and the original copies of their gospels would have been in circulation throughout the early churches. Luke's gospel was written while many of the eye witness of the life, crucifixion and resurrection of Jesus were still alive. Acts was certainly written down soon after Paul got to Rome the first time. Paul's letters were certainly in general circulation and read in the churches, as he instructed very early on. Just because our earliest manuscripts date from the 4th Century doesn't mean that there were much earlier copies that have been lost. The originals of Paul's letters were obviously written and distributed during Paul's actual ministry in the churches and during his imprisonment in Rome.
So, if there were illiterate people in the churches, they would have had literate people read the Scriptures plus Paul's letters to them, and so their faith was certainly based on the Jewish Scriptures, and, as we know now, Paul's letters which came to be recognised as New Testament Scriptures.
I understand your allegiance to the authority of the Church. I am not going to cause conflict by commenting on it. Where the Church gives Scripture truth to you, then I have no argument. We will have our disagreement about other doctrines that are not found in Scripture, but I understand the value that you put on Church tradition. Much of that tradition is there for the Church to run decently and in order, and there are many in the Church who have a sincere faith in Christ and Christ crucified and resurrected, and who is a competent judge to say that their faith is false? I'm not.
Even Martin Luther believed that the RCC was a true Christian church and that RCC people were true Christians. He just said that the pope was the anti-Christ, not the sincere people faithful to the gospel.
I know that some on this forum have accused me of being anti-Catholic, but I am not. I just don't support some of the doctrines and practices of some in the hierarchy of the Church. When I studied Catholic theology as part of my M.Div, I learned that there is more to unite us than to divide us.
But this doesn't mean that I am convinced enough to become Catholic. I stop short at loving my two cats, and the memory of my dearly departed cat Daisy (in the picture), so I can call myself a Cataholic!! :-)