"Messenger" of God is the symbol of Jesus Christ, who perfectly recognized the Will of God, was imbued with the Spirit of its Truth and devoted His life to its preaching, thus becoming God's "Messenger" to all nations.
God's "Messengers" are Patriarchs, Prophets, Apostles and all Righteous Men who proclaim God's Commandments and warn the nations against committing iniquity.
"Messenger" is a person who proclaims, presents to the nations God's Laws, implements the Covenants, Commandments, the Will of God that inspired him to proclaim the Revelations of God's Word that he has learned.