“Woe to you lawyers! For you have taken away the key of knowledge. You did not enter in yourselves, and those who were entering in you hindered.” Luke 11:52
Jesus used it. So did Paul (Romans 3:19,20), Timothy (1 Timothy 1:8–11), and James (James2:10). Stephen used it when he preached (Acts 7:53). Peter found that it had been used to open the door to release 3,000 imprisoned souls on the Day of Pentecost. Jesus said that the lawyers had “taken away” the key, and even refused to use it to let people enter into the kingdom of God.
The Pharisees didn't take it away. Instead, they bent it out of shape so that it wouldn't do its work (Mark 7:8). Jesus returned it to its true shape, just as the Scriptures prophesied that He would do (Isaiah 42:21). Satan has tried to prejudice the modern Church against the key. He has maligned it, misused it, twisted it, and, of course, hidden it—he hates it because of what it does. Perhaps you are wondering what this key is. I will tell you. All I ask is that you set aside your traditions and prejudices and look at what God’s Word says on the subject.
In Acts 28:23 the Bible tells us that Paul sought to persuade his hearers “concerning Jesus, both out of the law of Moses, and out of the prophets.” Here we have two effective means of persuading the unsaved “concerning Jesus.”
Let’s first look at how the prophets can help persuade sinners concerning Jesus. Fulfilled prophecy proves the inspiration of Scripture. The predictions of the prophets present a powerful case for the inspiration of the Bible. Any skeptic who reads the prophetic words of Isaiah, Ezekiel, Joel, etc., or the words of Jesus in Matthew 24 cannot but be challenged that this is no ordinary book.
The other means by which Paul persuaded sinners concerning Jesus was “out of the law of Moses.” The Bible tells us that the Law of Moses is good if it is used lawfully (1 Timothy 1:8). It was given by God as a “schoolmaster” to bring us to Christ (Galatians 3:24). Paul wrote that he “had not known sin, but by the law” (Romans 7:7). The Law of God (the Ten Commandments) is evidently the “key of knowledge” Jesus spoke of in Luke 11:52. He was speaking to “lawyers”—those who should have been teaching God’s Law so that sinners would receive the “knowledge of sin,” and thus recognize their need of the Savior.
Prophecy speaks to the intellect of the sinner, while the Law speaks to his conscience. One produces faith in the Word of God; the other brings knowledge of sin in the heart of the sinner. The Law is the God-given “key” to unlock the Door of salvation. See Matthew 19:17–22 comment and Romans 3:19,20.
“I do not believe that any man can preach the gospel who does not preach the Law. The Law is the needle, and you cannot draw the silken thread of the gospel through a man’s heart unless you first send the needle of the Law to make way for it.” Charles Spurgeon
Source: The Evidence Bible