Which came first? Was it the Mass or the Scriptures? According to the most conservative understanding of the writing of the New Testament, St. Mark may have been with Jesus and the Apostles and taken notes of what happened, but the Gospel of Mark did not likely come into a single reality until about A.D. 48 (at the absolute earliest). It is also possible that St. Paul wrote the Book of Galatians in the early 50's. This means that, at minimum, the individual churches had only the Old Testament (if they had copies of that) for at least the first 15 years. Then it took another 20 years for the rest of the New Testament to be written, and many decades more for it to be copied and disseminated throughout the various Churches that had been planted.
Thus, the average parish that was planted in the mid-30's did not likely have a copy of even a few books of the New Testament for as much as 40 to 50 years. It was completely possible for many people to have been born, lived, and died in the Catholic Church of the first century, and never heard or read any of the New Testament (readings for the Mass would have been exclusively out of the Old Testament at first). Yet, we know that they had the Mass from the Day of Pentecost (Acts 2:46-47). The Mass came first, and the Scriptures were a bonus that was added later as the need arose.
This is not a problem, or an accident, or a difficulty (unless you are a Protestant) in any way. This shows that the Mass is the primary means to learn the faith. Yes, the Apostles and the Bishops and Priests that they ordained, would have taught the people; obviously in a homily, but we also have evidence that there were "teaching sessions", some of which lasted hours. Therefore, the Mass is the foundation of the faith, and it is explained by the Old Testament, the Apostle's teachings, the authoritative Traditions that were established, and then finally, by the New Testament Scriptures.
The point of all of this is that we need to learn the Mass first if we are going to grasp what the Scriptures are talking about (and not the other way around). Someone who rejects the traditional Catholic Mass, cannot expect to understand what the New Testament is speaking about. Someone who perverts the Mass into something un-catholic is in the same boat. We must know that the sacrificial action of the Mass is the foundation. The Mass did not develop years later as an add-on. The Apostle's obeyed Jesus when He told them to "do this in remembrance of Me" by establishing the Mass. They also obeyed Him when He told them that later the Holy Spirit would lead them into all truth. They grasped that the Sacrifice is first, the explanation of the Sacrifice is something that follows after (for each of us in a unique way).
Those who corrupt the Mass, those who reject the Mass, those who neglect the Mass; they are all clouding their judgment in a way that prevents them from understanding the truth of God. It is as though they have closed their eyes and shut their ears to what God says (and we all know how hard it is to hit a target with your eyes closed). The Scriptures, New and Old Testaments, are wonderful. They are infallible and inerrant. They are the very words of God to us. Yet, they can only be understood in the context of the consistent and faithful celebration of the Mass.