Does 1 Corinthians 15:20-28 claim that ALL will be saved in time? Is there a particular group making that the cornerstone of their theology? I have had this explained to me as such and it just doesn't seem right to me.
There are groups who believe that ALL are destined to eternal life with God. But no, there are going to be many to whom Christ will say: "Go away, I never knew you." and many will be cast in the Lake of Eternal Fire.