The matter of the wedding garment is instructive. It would be a gross insult to the king to refuse to wear the garment provided to the guests. The man who was caught wearing his old clothing learned what an offense it was as he was removed from the celebration.
This was Jesus’ way of teaching the inadequacy of self-righteousness. From the very beginning, God has provided a “covering” for our sin. To insist on covering ourselves is to be clad in “filthy rags” (
Isaiah 64:6). Adam and Eve tried to cover their shame, but they found their fig leaves to be woefully scant. God took away their handmade clothes and replaced them with skins of (sacrificed) animals (
Genesis 3:7,
21). In the book of Revelation, we see those in heaven wearing “white robes” (
Revelation 7:9), and we learn that the whiteness of the robes is due to their being washed in the blood of the Lamb (verse 14). We trust in God’s righteousness, not our own (
Philippians 3:9).
Just as the king provided wedding garments for his guests, God provides salvation for mankind. Our wedding garment is the righteousness of Christ, and unless we have it, we will miss the wedding feast. When the religions of the world are stripped down to their basic tenets, we either find man working his way toward God, or we find the cross of Christ. The cross is the only way to salvation (
John 14:6).
For his crime against the king, the improperly attired guest is thrown out into the darkness. For their crimes against God, there will be many who will be consigned to “
outer darkness”—existence without God for eternity. Christ concludes the parable with the sad fact that “many are invited, but few are chosen.” In other words, many people hear the call of God, but only a few heed it.
https://www.gotquestions.org/parable-wedding-feast.html