The fine linen represents the righteous acts of the saints. Consider that the marriage analogy carries right through from the Old Covenant into the New. Under the New Covenant, the church is seen as a bride preparing for marriage.
There is a major difference, however, between the Old and New Covenant marriage analogies. In the Old Covenant, when Israel agreed to God's proposal, and Moses performed the ritual described in Exodus 24, they were married. When we enter into the New Covenant, we are not married yet. We are like a bride preparing for marriage, even though we have already agreed to the New Covenant. God has made this change to resolve the weakness of the first covenant, which will be eradicated before the actual ceremony and union take place.
Revelation 19 is the announcement that the bride is now ready and the marriage can take place. There are four things that a marriage relationship must have to really be successful:
1) A marriage must have love. A loveless marriage is a contradiction in terms.
2) A marriage must have intimate communion—so intimate that the bride and groom become one flesh. The two become one.
3) A marriage should have joy. This will be a natural result if love exists in the marriage. The joy of loving and being loved is like nothing else.
4) A marriage must have fidelity, loyalty, and faithfulness. No marriage can last without it.
The weakness of the first covenant will be resolved—eradicated—before the actual ceremony and union take place. This time, Christ will be married to a wife who has already proved that she loves Him, that she is capable of intimate communication, that she is happy with Him as her Husband, and that she is faithful in every aspect of her life.
Notice how attention is drawn to her preparations, as well as her righteous acts. Could her righteous acts have anything to do with the preparation? Absolutely. Could it have anything to do with her being qualified? Absolutely. Works—her righteous acts—are represented here.
We should not be misled into thinking that her deeds, her righteous acts, have earned her salvation. All through the Bible, it maintains a delicate balance between grace (what is given) and obedience (the proper response). Here, that balance is shown by the wife's garments being granted to her. She has worked, but the gift is still given.
It takes work to make a marriage successful. It takes work to make our relationship with God successful. If we do the right kind of works, there is no doubt that the relationship will be successful, and God will be well pleased with us. And we will enter His Kingdom.