I've always wondered what the wedding garment signified in the following parable, as one would want to be sure that they had the proper wedding clothes....

22 And Jesus answered and spoke to them again by parables and said: ² “The kingdom of heaven is like a certain king who arranged a marriage for his son, ³ and sent out his servants to call those who were invited to the wedding; and they were not willing to come. ⁴ Again, he sent out other servants, saying, ‘Tell those who are invited, “See, I have prepared my dinner; my oxen and fatted cattle are killed, and all things are ready. Come to the wedding.”’ ⁵ But they made light of it and went their ways, one to his own farm, another to his business. ⁶ And the rest seized his servants, treated them spitefully, and killed them. ⁷ But when the king heard about it, he was furious. And he sent out his armies, destroyed those murderers, and burned up their city. ⁸ Then he said to his servants, ‘The wedding is ready, but those who were invited were not worthy. ⁹ Therefore go into the highways, and as many as you find, invite to the wedding.’ ¹⁰ So those servants went out into the highways and gathered together all whom they found, both bad and good. And the wedding hall was filled with guests.

¹¹ “But when the king came in to see the guests, he saw a man there who did not have on a wedding garment. ¹² So he said to him, ‘Friend, how did you come in here without a wedding garment?’ And he was speechless. ¹³ Then the king said to the servants, ‘Bind him hand and foot, take him away, and^[a] cast him into outer darkness; there will be weeping and gnashing of teeth.’
¹⁴ “For many are called, but few are chosen.”

The following quote from Randy Alcorn's Safely Home, suddenly made this clear for me -
"Jin looked up, 'We are his church.  We are that bride!  We are dressed in the righteousness of Yesu.  We wear the spotless wedding gown of his holiness."  (Safely Home pg 136)

We don't get in on our own righteousness, but only clothed in His righteousness.  I don't know how someone can be in the faith so long and not really understand simple truths like this - it all makes so much sense but somehow even though other Scriptures speak of being dressed in His righteousness and many hymns, it had never clicked for me before in this particular parable until I read the above quote.