In another thread, I mentioned how, from the time the apostles Thomas and Bartholomew came to India until about the fourth century or so, my best guess would be that the local Church started by those apostles had, at best, the entire Old Testament (whether or not it included the deuterocanon I cannot say for sure) and just the Gospel of St Matthew from the New Testament.
Certainly I would agree with you that it was a shame they didn't have the other New Testament books, but my question to you is this: did they lack anything necessary in order to know Christ, believe in him, and be saved?
No. They knew Christ, they believed in Him and lived a very holy life indeed.
I read about some Saints in the east and the west and they had so much love for God and at the same time some of them weren't able to read at that time.
And how were they able to have all this without the full Bible (assuming they even had as much as I said they did)?
Here is an answer from the Bible itself.
2 Peter 3:16
16 He writes the same way in all his letters, speaking in them of these matters. His letters contain some things that are hard to understand, which ignorant and unstable people distort, as they do the other Scriptures
, to their own destruction.
Here is clearly Saint Peter saying that Saint Paul's writings are Scriptures.
And here another answer for your point in general.
" Did the Early Christians Possess the Scriptures?
Question: You need the guidance of Sacred Tradition to help you figure out the truth. In the early church the people could not have listened to the apostles speak and then gone home to check what they said in their Bibles. People had to accept what the apostles told them by word of mouth because it had not been written down or put into a text for anyone to read.
Answer: Over the past couple of years I have encountered every kind of argument seeking to undermine the centrality and the ultimate authority of the Holy Bible. A popular argument notes that the early Christians did not have the complete Bible and that it took almost four centuries before the canon of Scripture was finally and officially recognized. Hence, the implication that the Bible could not be that important.
This argument is flawed because it fails to recognize that the church was going through a maturation phase, and it is rather silly to belittle the perfection of the mature state on the grounds that it was not always that way. It is like arguing that we don’t really need our lungs because there was a time when we lived well without them in our mothers' womb! Or that it was not really necessary that Christ should come to this world because before him, God still spoke to His people by the prophets!
We are living in an age when we have the complete written Word of God in our hands. What, or who can replace the Bible in the heart of the church? Or who can claim to have equal or higher authority to the Word of God?
You seem to be preoccupied that Evangelicals do not blindly accept the Church’s teachings but insist on verifying everything by the Bible. Well, we have biblical precedent for doing so. Once an apostle of Jesus Christ and his associate preached the Gospel in a certain city. They proclaimed the Gospel and the people listened attentively. But the people of that city did something more. Every day they studied the holy scriptures to check whether the things they heard were true or not.
What do you think? Isn't it a little bit arrogant and presumptuous to question the teaching of an apostle? Isn't the teaching magisterium of the apostle the highest authority on earth? Is it not the prerogative of the apostle to interpret the Bible infallibly, rather than for common, ordinary people to check his teaching by the Bible? And how can they understand the Scripture since they didn’t have the guidance of 'Sacred Tradition'?
As you may have realized, I am referring to the Bereans mentioned in Acts 17:10-12. Luke says (v 11): 'These were more fair-minded than those in Thessalonica, in that they received the word with all readiness, and searched the Scriptures daily to find out whether these things were so.'
Two important points can be deduced from this passage:
For the Bereans the ultimate and highest authority was the holy Scriptures. They did well to receive the words of the apostle for he is the messenger of Christ; but they did better to check out his doctrine by the standard of the written Word of God. As a Protestant, I believe that every Christian must submit to the teaching authority of the teachers that Christ gave to His church as far as their teaching is consistent with the Holy Scriptures.
The Berean believers already had the Scriptures (evidently not the whole of our Bible) to which they could refer. And they knew that they were the Word of God even before any pope or council declared them to be so. Many are deceived by the Catholic propaganda which insists that a person could not know what is authoritative Scripture if it was not for the authority of the church. "
About how they knew about Christ ? They knew by the Apostles, however, many people went back to the Scriptures like mentioned above. Also, that was the time of the Apostles, now thanks to God, we have the full Bible, and again as mentioned above, we don't need anything else beside it. We are mature now and God is guiding His followers.
So here is two types of answer to your question