Many Christians are under the false impression that, simply because they have made a single profession of faith, they are instantly and immediately and forever "cleansed" from all sin, and that this makes them "white as snow," alluding to the first chapter of the Book of Isaiah. By this, many mean to imply that they are not only cleansed from past sin – which is TRUE if we are Born Again and pledge our lives to serve and obey God in sincere repentance. But some mean this to apply to all FUTURE sin as well. And this is false.
Inherent in this is the belief in a verbal profession – the magical words that, by merely speaking them, not only "saves" them (i.e. they gain instant entry into Heaven when they die) but absolves them from doing "Works" which some falsely see as "filthy rags” and somehow trying to “add” to one’s salvation. Which is, for them, a foregone conclusion.
They are mistaken on several counts, and are guilty of twisting the meaning of Scripture to make it mean what they wish it meant.
The verses recited by Isaiah speak of God's disgust at the people of Israel because they did NOT, in fact, do Good Works and were not acting in a righteous manner.
Verse 18, which is often quoted out of context and in isolation, reads: "Come now, let us reason together, says the Lord: though your sins are like scarlet, they shall be as white as snow; though they are red like crimson, they shall become like wool."
But this is not a promise by God to MAKE a person instantly pure and righteous by saying mere words (something Jesus himself says. In fact, earlier in the chapter, God tells Israel that its words and prayers, offered by those who will not do righteous deeds, were pointless:
Verses 1:15-16 read: "When you spread out your hands, I will hide my eyes from you; even though you make many prayers, I will not listen; your hands are full of blood. Wash yourselves; make yourselves clean; remove the evil of your deeds from before my eyes; cease to do evil, learn to do good; seek justice, correct oppression; bring justice to the fatherless, plead the widow’s cause."
(Does this not sound exactly like the preaching of Jesus, who urged us to do good and cease doing evil?)
The promise to make one white as snow is a good promise, but it's a CONDITIONAL one by God, based upon us doing WORKS. Remember, the verse JUST before it (16-17) reads as a call to make oneself pure by DOING good:
"Wash yourselves; make yourselves clean; remove the evil of your deeds from before my eyes; cease to do evil, learn to do good”
Verses 19 and 20 after it read: "IF you are willing and obedient, you shall eat the good of the land; but IF you refuse and rebel, you shall be eaten by the sword; for the mouth of the Lord has spoken."
Therefore, while we are made “white as snow” when we first repent of our sins before God, and, after seeking His forgiveness, we receive it, we may definitely get muddy once again through our subsequent actions.