Hey Tom,
Us Unitarians (biblical that is) have a rough row to hoe. On the one hand, the things related to the "secret of God" (1 Corinthians 2:1 "musterion" instead of marturion ("testimony")) were "hid in God", "hid from ages and generations", "kept secret since the ages began" and "not made known unto the sons of man". On the other, Christendom has in its two bit brain that Jesus knew everything. He did not. He also was a man; nay "the son of man" (that Hebraic expression epitomizing humanness).
Progressive revelation shows us that what came on the day of Pentecost was not what was expected in prophecy, but prophecy will be fulfilled. Jesus could only speak of what he knew and he knew of the "last days", the "great tribulation", the "day of the Lord", etc, but he did not know what was coming as the intercalation (large theological BS meaning "commercial interruption" for TV lovers) of events. A secret made known unto the Christian prophets, Paul being tapped to write it all down. Peter referring to Paul's writings as kinda "hard to understand". Jews had a hard time with Pauline theology.
Anyway, not knowing something is not a sin (think Jesus here) and prophecy will come to pass (think Joel's prophecy about the spirit that Peter referred to on Pentecost...and he wasn't the Pope yet so he couldn't have been speaking Ex Cathedra...a little humor for my Roman Catholic compatriots).
Lots of stuff to sort out
RE