In this text the author recalls many of the themes scattered through the epistle – angels, heaven, perfection, the new covenant, and the sprinkled blood – to summarize the underlying motivation to persevere, namely, the superiority of the new covenant and of Jesus Christ. He illustrates this by presenting the old and new covenants as two mountains. They had not come to Mount Sinai but to Mount Zion. Mount Sinai, where the law was given and the old covenant enacted, was terrifying because of God's holiness which separated Him from His people. Sinai, with its fearful power and foreboding awe, could not deal with sin in the face of wrath. Mount Zion, however, the city of God, the heavenly Jerusalem, is where God's people gather in His presence joyfully and without fear, because we have come to Jesus, the greater Mediator of a greater covenant; He secures complete and final forgiveness of sins, ushering us into the presence of God. Believers can persevere and finish the race because we have come to Mount Zion which is greater than Mount Sinai.
The contrast between the environment of these two mountains is striking and colors the differences between the old and new covenants. The first mountain could be touched, felt, seen, and heard (v 18-19), yet it was so terrifying that even the law-giving mediator, Moses, trembled to approach it (v 21). The second mountain is invisible and accessible by faith, yet it could be approached with joy because of the Mediator of a new covenant, Jesus Christ. This is where our race ends – in the holy presence of God, where there is fulness of joy and a ceaseless celebration with the redeemed, God's holy angels, and Jesus.