Messianic messages and prophecies are scattered throughout the Psalms, notably in Psalm 110. The question arises: Did Psalmists and Old Testament prophets fully comprehend what they were writing about in these prophecies, or was it largely a mystery to them?

Psalm 110 is titled "The Priestly King." It is a Psalm by David where he refers to Jesus not as his son, even though Jesus would be a descendant, but rather as his Lord. David knew that Jesus would eventually come through his royal bloodline, making Him a King. This lineage is confirmed in the genealogies written in Matthew 1 and Luke 3, where David features prominently. We also find this in the Old Testament, notably in Psalms 89:3-4:

3 "The LORD said, 'I have made a covenant with my chosen one; I have sworn an oath to David my servant: 4 'I will establish your offspring forever and build up your throne for all generations.'"

This theme is echoed in other Old Testament prophecies like Ezekiel 34:23-24, Isaiah 9:6-7, Jeremiah 23:5-6, and Micah 5:2.

In Psalm 110, David writes: 1 "This is the declaration of the LORD to my Lord: 'Sit at my right hand until I make your enemies your footstool.'"

Here, David, the king of Israel at the time, makes reference to two Lords, talking essentially about Jesus Christ and God the Father. Verses 2-6 discuss Jesus being a Priest according to the pattern of Melchizedek and King, with authority over all the world.

Looking at Romans 16:25-26, we see a confirmation of the limited Old Testament knowledge of Jesus: 25 "Now to him who is able to strengthen you according to my gospel and the proclamation about Jesus Christ, according to the revelation of the mystery kept silent for long ages 26 but now revealed and made known through the prophetic Scriptures, according to the command of the eternal God to advance the obedience of faith among all the Gentiles."

David, and others like Isaiah, probably did not fully understand what they were writing. They had hints and were under the influence of the Holy Spirit. To support this, let's consider Jesus' interaction with the Pharisees in Matthew 22 and Mark 12, where He discusses Psalm 110:

41 "While the Pharisees were together, Jesus questioned them, 42 'What do you think about the Messiah? Whose son is he?' They replied, 'David’s.' 43 He asked them, 'How is it then that David, inspired by the Spirit, calls him ‘Lord’: 44 'The Lord declared to my Lord, Sit at my right hand until I put your enemies under your feet'? 45 'If David calls him ‘Lord,’ how, then, can he be his son?'"

This shows that David and the prophets were inspired by the Holy Spirit. The scriptures can be trusted as they are guided by God Himself, affirmed by 2 Peter 1:16-21 and 2 Timothy 3:16-17. Peter emphasizes this in 2 Peter 1:20, saying, "Above all, you know this: No prophecy of Scripture comes from the prophet’s own interpretation, because no prophecy ever came by the will of man; instead, men spoke from God as they were carried along by the Holy Spirit."

Like John's visions in Revelation, David likely only knew a portion of what would happen. He knew he was under the Spirit’s guidance when writing Psalm 110.

Hebrews 1 is based on Psalm 110, and it mentions: Heb 1:1-2 "1 Long ago God spoke to our ancestors by the prophets at different times and in different ways. 2 In these last days, he has spoken to us by his Son."

This passage from Hebrews aligns with the idea that while the Old Testament prophets had insights, the full revelation of Jesus Christ came later, fulfilling their prophecies.

In my opinion, and some might differ, I do not think they knew or they kept is silent, as the bible is without error and that is what it says in Romans 16, it was a mystery kept silent for long ages. But, we surely can ask David and Issiah and Moses and the others what and when they knew about Christ coming to the world to die on a cross.