Metánoia (Repentance): A Major Theme of the Gospel of Matthew

Matthew describes the beginning of Jesus's ministry with the summary words, "μετανοεῖτε (repent/turn), for the kingdom of heaven is at hand" (3:2; 4:17). Why does Matthew use this command, μετανοεῖτε, at the beginning of his ministry, and how does it relate to the rest of the Gospel? What do μετανοέω and μετάνοια mean? Scholars have stated that μετανοέω in 4:17 has critical value for understanding Matthew because the verse functions as a summary statement (or key phrase) of Jesus's public m...