Zacchaeus was tax collector, which was a hated profession in his day, as was a Jew who had vowed to support the Roman government. Tax collectors were traitors to their people, often taking advantage of them by overcharging taxes and pocketing the excess.
Jesus has entered Jericho on his way to Jerusalem to be tried, convicted and crucified. He finds Zacchaeus in a tree (which he has climbed in order to see Jesus above the crowd) and he does a crazy thing: Jesus, a noted and respected Rabbi, calls to this despised tax collector and asks him to come down and welcome Jesus into his home.
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