Since the Kingdom of Heaven is compared to a king hosting a banquet, all the other characters who appear in the parable can be compared to different types of people who respond to the call of the kingdom. Imagine the frustration of the king when those he so lovingly favoured with an invitation and whom he expected to be with him turned down the kingly invite and refused to go to the feast. What great preparations the Lord of the kingdom had made to receive them into his abode!
Yet they made themselves unworthy to be the royal guests. The second group of guests who were invited to the feast from the streets represent the people to whom the kingdom is offered as a free gift. These guests might not have considered themselves worthy to be invited by the king. Feeling greatly honoured they dressed up and went to the feast to share in the joy of the king! However, there was one who came without a wedding garment and he was thrown out: the doors of the kingdom are open to all, but nobody can enter there unworthily, without wearing the garment of justice, mercy and humility.