In contrast to the frightening scene at Sinai is the wonderful glimpse of the heavenly Zion (Hebrews 12:22-24). This assemblage is now gathered in heaven but will all become a glorious reality on earth when the "heavenly Jerusalem" descends out of heaven to the new earth (Revelation 21:2-7).

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8