Who inspired the Old Testament prophets to write their prophecies?
The Spirit of Christ inspired the Old Testament prophets as they wrote. Peter writes that those prophets inquired and searched diligently concerning the salvation and grace to come, and the Spirit of Christ within them testified beforehand of Christ's sufferings and the glory that should follow.
Les teaches from I Peter 1:10-12 that the Old Testament prophets wrote by inspiration, with the Spirit of Christ in them. They inquired and searched diligently about the salvation and grace that should come, and they searched what manner of time the Spirit of Christ within them signified. The Spirit testified beforehand the sufferings of Christ and the glory that should follow. Les also points to Daniel, who asked the meaning, but the Lord told him to shut up the book because it was not for him to know; when the end of time comes, they will know. The prophets, including Isaiah, Jeremiah, and Ezekiel, wrote by inspiration but could not put it all together.
Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.
What were the Old Testament prophets searching for when they wrote their prophecies?
The Old Testament prophets searched diligently to understand the salvation and grace that was to come, and what manner of time the Spirit of Christ in them was signifying when He testified beforehand of Christ's sufferings and the glory that would follow. They wrote by inspiration but could not fully put it all together.
Did the Old Testament prophets understand the prophecies they wrote about Christ?
No, the Old Testament prophets did not fully understand the prophecies they wrote about Christ. They searched diligently, inquiring what manner of time the Spirit of Christ in them signified, but God did not reveal the full meaning; Daniel was told to shut up the book until the end times.