From Revelation by Peter S. Williamson commenting on 22:14:
The seventh and last †beatitude makes clear that the call to conversion is truly good news: Blessed are those who wash their robes. A previous vision revealed people before the throne of God who had “washed their robes and made them white in the blood of the Lamb” (7:14). This blessedness is not the result of a perfect moral record, nor is it available as a result of merely human moral effort. It belongs to those who turn from evil to God and receive cleansing and grace from the sacrifice of Christ through baptism (Acts 22:16; Eph 5:26) and ongoing repentance: “If we walk in the light as he is in the light, then we have fellowship with one another, and the blood of his Son Jesus cleanses us from all sin. . . . If we acknowledge our sins, he is faithful and just and will forgive our sins and cleanse us from every wrongdoing” (1 John 1:7, 9). Jesus explains a twofold right that belongs to the blessed as a consequence. First, they have access to the tree of life, eternal life, previously kept back from the human race because of the sin of our first parents (Gen 3:22–24). Second, they enter the new Jerusalem through the gates—they have the right to dwell there as true citizens.