Let’s talk a little about the first reading. Paul had been arguing with Pharisees who held that it was only by a strict observance of the Mosaic Law that a person could be saved.
Against their stand he here pointed out that Abraham, whom they revered as the father of their race and of their religion, had been saved by just believing; and that took place five hundred years before Moses and his Law.
The Pharisees were requiring much more than the observance of the Law on Moses as found in the Bible. As well, they were requiring believers to observe tens of thousands of prescripts that had been added to the Law over the previous 500 years. The Hebrew name for those prescripts added to the lawwas the Mishna.
Martin Luther misunderstood what St. Paul was saying. He took it that in saying there was no need to observe the Mishna, Paul was not telling us we could disregard the Ten Commandments and the Sermon o the Mount. No, as the Letter to the Hebrews pointed out, a person cannot be saved by faith alone if his behavior is sinful.
When the Bible speaks of our need for faith, it is usually referring to our need to trust God. That need ties in with today’s Gospel where Jesus speaks of our being saved by acknowledging him. He says anyone who denies him will be denied before the angels of God.