Blindness: An inability to see. "In Scripture blindness is a term frequently used to denote ignorance or a want of spiritual discernment . . . a lack of understanding resulting from unbelief" (Unger's Bible Dictionary, "Blindness").
Human nature: The characteristics, tendencies and behavior of a human being. At birth human nature is fundamentally neutral. However, over time and under the influence of Satan, human nature is predominately characterized by vanity, jealousy, greed and self-gratification. As creatures of choice, we are enjoined and expected to resist the pulls of base self-motivation and respond to the leading of God's Spirit.
Messiah: A Hebrew word meaning literally "anointed one," synonymous with the Greek word christos, translated Christ. "In ancient Israel both persons and things consecrated to sacred purposes were anointed by having oil poured over them . . . The Israelites did not think of crowning a king but of anointing him when he was enthroned . . . [The future Messiah] is to destroy the world powers in an act of judgment, deliver Israel from her enemies, and restore her as a nation. The Messiah is the King of this future kingdom to whose political and religious domination the other nations will yield. His mission is the redemption of Israel and His dominion is universal. This is the clear picture of the Messiah in practically all of the OT passages which refer to Him" (The Zondervan Pictorial Bible Dictionary, "Messiah").
Prophecy: A prediction of events to come. "A discourse emanating from divine inspiration and declaring the purposes of God, whether by reproving and admonishing the wicked, or comforting the afflicted, or revealing things hidden; esp[ecially] by foretelling future events" (Revised Thayer's Greek English Lexicon, "Propheteia").
Sign: "The rendering of several Hebrew and Greek words, which usually denote a miraculous, or, at least, divine or extraordinary token of some (generally) future event" (Unger's Bible Dictionary, "Sign").