Why is the wedding garment important in the parable?

In the parable, the wedding garment represents the righteousness of Christ that is essential for acceptance at God's feast. When the king sees a guest without a wedding garment, he commands that he be cast out, symbolizing the necessity of being clothed in Christ's righteousness to avoid judgment. This reflects the Reformed understanding that we are not justified by our works but solely through faith in Christ, whose righteousness is imputed to believers, allowing them to stand acceptable before God. Thus, the wedding garment underscores the critical need for a spiritual covering in Christ for salvation.