ISB ~ Hebrews 12 v18 - 24
The Old Covenant is contrasted with the New:they are represented by different mountains (Sinai/Zion), different assemblies (Israel/Church), different responses (fear/ worship), different locations (earth/heaven), and different mediators (Moses/Jesus). The author is launching his final appeal to keep readers from sliding back into Judaism.
See introduction:Destination and Purpose.