Hebrews is easy to preach because its form is much more like a sermon than an epistle (letter). At the heart of its message is an impassioned plea not to leave the Christian faith for another, and so in order to be convincing the author of Hebrews makes many comparisons between Christ and all the things of the Old Testament he is superior to. We have already seen that Christ is superior to the angels, and that through suffering he becomes the perfect founder of our faith. Chapter 3 begins this way:
Therefore, holy brothers, you who share in a heavenly calling, consider Jesus, the apostle and high priest of our confession, who was faithful to him who appointed him, just as Moses also was faithful in all God’s house. For Jesus has been counted worthy of more glory than Moses—as much more glory as the builder of a house has more honor than the house itself. (For every house is built by someone, but the builder of all things is God.) Now Moses was faithful in all God’s house as a servant, to testify to the things that were to be spoken later, but Christ is faithful over God’s house as a son. And we are his house if indeed we hold fast our confidence and our boasting in our hope. Hebrews 3:1-6
Moses led the Hebrew people through the wilderness. He directed and provided for them. He brought to them God’s Law. Jesus is leading his followers through this present wilderness. He not only leads, guides and directs, but is our provider in many ways. Jesus brings us God’s grace. Moses brought the Law; the Law does not make one righteous. Jesus shares God’s mercy, forgiveness and salvation. Jesus is greater than Moses.
The appeal is definitely to first century Christians who converted from Judaism. The temptation may be strong to abandon Christianity and return to the Jewish faith, which was not heavily persecuted by the Romans the way Christian followers were. Hebrews goes on to make many comparisons between Jesus and the Law, temple, high priest, animal sacrifice and so on. For modern-day Christians, studying how God related to his people in the Old Testament compared to what Jesus does on the cross gives us a better understanding of his office. Jesus offers a better covenant, but how could one know that without studying both? One could certainly read only the New Testament (even just the Gospel of John) and become a Christian believer. But to fully appreciate everything the message that God is sharing with us, we must read and study the whole Bible. The whole Bible tells the story of a holy God relating to a fallen and sinful people, and the heart of that message is Jesus.
The rest of Heb 3 and the beginning of 4 reminds us that those Moses led out of Egypt did not enter the land of promise because of their disobedience. The rest that remains for the people of God in this age is greater than the promised land of Canaan.