You might say, “I must be saved. I believe that Jesus died and rose again. I have an understanding of biblical theology. Certainly someone who believes in Jesus can’t be lost.”
Sure, knowledge of Jesus is necessary for salvation but knowledge alone does not guarantee salvation. You can know about Jesus, even the details of His life, death and resurrection. You might pass a test on basic biblical facts and still be without Christ.
James 2:19 says, “Thou believest that there is one God. Thou doest well. The devils also believe; and tremble!” The demonic hordes of hell have a great intellectual understanding of theology. Satan quotes the Scriptures. Yet they will never be saved! They are the enemies of God.
The book of Hebrews is written both to believing Jews and Jews who are close to believing on Jesus. That second group had an understanding of the gospel, yet because many of them were about to turn away, the writer says clearly what takes place in the verses for today.
It is possible to know about God without knowing God. So we should never rest our salvation on our intellectual understanding.