Psalm 121 is what is referred to as a song of degrees. It was typically sung on a journey, sometimes to Jerusalem when a traveler was ascending toward the city. David opens the psalm with the words, “I will lift up mine eyes unto the hills, from whence cometh my help” (Psalm 121:1).
David talks throughout this psalm about the LORD keeping his people and preserving them into eternity. Although there is no specific reference to the Messiah, it is possible David was referring to the hill of Calvary on which his savior would die.
One of the meanings of the word translated hill is mount. Jesus spent time teaching his disciples on the mount of Olives and gave his most famous discourse there, what is referred to as the Olivet Discourse. The idea that David’s help would come from the hills is rooted in the fact that Moses spoke to God face to face on mount Sinai and God chose to make a great revelation known to him there.
The book of Hebrews ties together the Old Covenant which applied to David and the New Covenant which applies to believers in Christ by showing that the instructions Moses received for the Tabernacle were to serve as an example and shadow of heavenly things. Speaking of the heavenly kingdom of God, it says in Hebrews 12:18-23:
For ye are not come unto the mount that might be touched…But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, to the general assembly, and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of the just men made perfect.
According to the notes on Hebrews 12:23, it is believed that the spirits of the just men made perfect were pre-Christian believers such as Abel and Noah. “They are referred to as ‘spirits’ because they are waiting for the resurrection of the just because God credited them with righteousness, as he did Abraham (see Romans 4:3). Actual justification was not accomplished, however, until Christ made it complete by his death on the cross (see 11:40, Romans 3:24-26; 4:23-25).”
It is unknown how much God revealed to these pre-Christian believers, but it seems likely that they knew there would be a human sacrifice and that the Messiah would be referred to as the perfect lamb of God that would shed his blood to take away the sins of the world. Whether or not David had a vision of Calvary or mount Sion in mind when he wrote Psalm 121 is unclear, but his reference to eternity leaves no doubt that the help which would come from the LORD would be the LORD himself.