You have not come to a mountain that can be touched and that is burning with fire...But you have come to Mount Zion to the heavenly Jerusalem, the city of the living God.You have come to thousands upon thousands of angels in joyful assembly.
In the OT we see the picture of a scary God, one who the people honor and fear. He appears to them in fire, trembling mountains and earthquakes. But we have Christ, the mediator of a new covenant. We have the church of the firstborn.
We have received a kingdom that cannot be shaken. Worship God in reverence and awe.