The book of Hebrews was written to Jewish Christians. Jews who came to faith in Jesus Christ were persecuted by Rome and also ostracized by their unbelieving friends and family. As a result, many were pressured to return to the law and the bondage of legalism.
A lot of religious groups do the same thing today. They say, “You have to believe in Jesus Christ and be baptized in our church,” or, “You have to knock on so many doors to win others to Christ,” or, “You have to give money.” This leads to legalism.
The book of Hebrews showed the Jewish believers—and it shows us today— that Jesus is better than any good works we can do. He is better than the angels, better than Moses, better than Aaron. He is a better sacrifice, a better sanctuary, a better covenant, a better promise, a better resurrection, a better hope. Salvation is not by works—it is through faith in Jesus alone.