Revelation 19:8 And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints.
At the Marriage Supper of the Lamb our Lord gives the Bride of Christ fine linen, clean and white. The promise is that the Bride, the Church, we the believers, are granted a fine, white, beautiful wedding dress. It is somewhat surprising when plain-looking women can be made up and dressed up to look stunning for their wedding day. Brides are always pretty.
That is the picture God wants to paint for us, so that we may see ourselves as God sees us: He sees the beauty of holiness in us. The ”fine linen” is defined as righteousness of saints. Wedding finery can just be outward covering of flaws and blemishes with nothing changed inwardly. However, the outward clothing in this case is caused by, and evidence of, inner beauty. The righteousness of saints (linen) reflects the inner beauty, the holy character, of the person. The person has been cleansed of sin by the blood of Jesus, purified and sanctified by faith.
We are saints now, although we don’t see it since we are still sinners at the same time. But we believe the promise. We will be arrayed in righteousness for all to see later, at the marriage feast. And we believe the promise. It is helpful for us to see by faith what God sees, righteousness of saints.