Among the things I really like about the Greek Orthodox calendar of saints is its inclusion of the Old Testament saints as well as the Christian saints. It seems to me that the old prophets should be every bit as revered as the apostles.
Haggai was living in Jerusalem around 520 BCE and after the Persians permitted repatriation. At the time, Zerubbabel the Governor of Judah and Joshua the High Priest were arguing against the rebuilding of the Temple, saying that the time had not yet come to rebuild the Lord's house.
Haggai's answer: “Is it a time for you yourselves to be living in your paneled houses, while this house remains a ruin?”
I like this guy, and having just read an account of the hand-to-hand fighting in the Court of the Gentiles that Titus' legions experienced before conquering the city, I'd say Haggai was right about the value of the building project.