The King of Salem of Genesis 14:18-20 prefigures the Prince of Peace of Isaiah 9:6.
Because of the Messiah's present position as Prince of Peace, the future glory of the saints is guaranteed.
Only the One who is "a priest forever after the order of Melchizedek" can "save to the uttermost."
The completeness of the number of the Messiah's people is certain. No one in Heaven or earth can change it.
It is "My peace" - a one-of-a-kind peace, not a peace "as the world gives" - that the Prince of Peace freely bestows upon His people.
The angelic announcement of Luke chapter 2 is indeed stupendous.
By human standards, the audience for the greatest announcement in history could not have been more poorly chosen. But not by God's standards.
How does the fear of the Christian differ from that of the lost?
Jehovah repeatedly allayed the fears of Abraham, Isaac and Jacob that He would not keep His promise of the Messiah through them.
God's Messianic promises to Daniel, Zacharias, Mary, and Joseph all came with the words "Fear not." Each time this pronouncement had to do with fear of the future.