Everyone who has a hope of seeing God as He is purifies himself just as God is pure.
In Romans 3:10-18, you can read what Kåre J. Smith describes as an X-ray view of a person, where Paul explains that there is none righteous, no not one. All of this iniquity entered into the flesh because of the fall.
Nevertheless, John says in his first letter, “Behold what manner of love the Father has bestowed on us, that we should be called children of God!” and further on, “we shall be like Him, for we shall see Him as He is.” In the next verse, he talks about what conditions are required for this to happen: “And everyone who has this hope in Him purifies himself, just as He is pure.”
In 1 Peter 1:22, God’s Word says something about how to purify ourselves: “Since you have purified your souls in obeying the truth….” It is by being obedient to the truth about ourselves, as God Word shows us, that we are purified to become like Him.