Gamaliel is a great example of the immense impact that a teacher— even an unbeliever—can have on the world.
Gamaliel does not appear to have been a Christian, but through his student Saul/Paul he may well have had the greatest positive influence on Christianity of any unbeliever in history.
The Bible first mentions Gamaliel in connection with Peter and the other apostles, who were arrested for preaching in the name of Jesus Christ. Gamaliel, a respected teacher of Jewish law, persuaded the Sanhedrin to release the apostles and leave them alone—because if they were not from God, their cause would die out, just as many others had. But if they were from God, the Jewish leaders would be fighting against God Himself (Acts 5).
The only other time the Bible mentions Gamaliel is in a speech made by the apostle Paul. When Paul arrived in Jerusalem at the end of his third missionary journey, many Jews accused him of various offenses. Paul began his defense by recounting that he was educated by Gamaliel and was thoroughly trained in the law. He zealously persecuted Christians, but later the Lord appeared to him, and he became a Christian himself. Paul’s thorough training in the law under Gamaliel’s teaching eventually helped Paul to see how the law points to Jesus Christ, who fulfilled the law for us. Paul’s ministry has helped to spread the good news of Jesus Christ throughout the world.
Gamaliel was the grandson of Hillel, a famous teacher of religious law. Among other things, Hillel, who lived shortly before the time of Jesus, became well-known for stating a saying very similar to the Golden Rule (Matthew 7:12): “What is hateful to you, do not do to your fellow: this is the whole Law; the rest is the explanation; go and learn.”