It is striking because here the survivors of God’s wrath did the washing themselves. In other words, the emphasis lies on the person’s own responsibility to benefit from Christ’s work on the cross. Just as the people of Israel were responsible to smear blood from the Passover lamb around the door of their homes (and so express their faith in the benefits of the coming Passover Lamb and escape God’s judgment on Egypt), so in the New Testament era all are responsible to embrace in faith the preaching of the gospel (Revelation 6:1–2) and so be washed in the blood of the Lamb. Those who do so will persevere in the face of every expression of God’s judgments on sin.
14 I said to him, “Sir, you know.” And he said to me, “These are the ones coming out of the great tribulation. They have washed their robes and made them white in the blood of the Lamb.