They have washed their robes and made them white in the blood of the Lamb. Rev 7:14
God has only one requirement for entrance into heaven: that we be clothed in Christ.
Listen to how Jesus describes the inhabitants of heaven: "They will walk with me and wear white clothes, because they are worthy…" (Rev 3:4 ).
Listen to the description of the elders: "Around the throne there were … twenty-four elders… They were dressed in white and had golden crowns on their heads" (Rev 4:4 )…
All are dressed in white. The saints. The elders… How would you suppose Jesus is dressed? In white? … "He is dressed in a robe dipped in blood, and his name is the Word of God" (Rev 19:13 ).
Why is Christ's robe not white? Why is his cloak not spotless? Why is his garment dipped in blood? … Paul says simply, "He changed places with us" (Gal 3:13 )…
He wore our coat of sin to the cross.
When Christ Comes (by: Max Lucado)