Here's the whole thing, as you would have seen, had you been honest enough to quote in in context:
14What good is it, my brothers, if someone says he has faith but does not have works? Can that faith save him?
15If a brother or sister is poorly clothed and lacking in daily food,
16and one of you says to them, “Go in peace, be warmed and filled,” without giving them the things needed for the body, what good
b is that?
17So also faith by itself, if it does not have works, is dead.
18But someone will say, “You have faith and I have works.” Show me your faith apart from your works, and I will show you my faith by my works.
19You believe that God is one; you do well. Even the demons believe—and shudder!
20Do you want to be shown, you foolish person, that faith apart from works is useless?
21Was not Abraham our father justified by works when he offered up his son Isaac on the altar?
22You see that faith was active along with his works, and faith was completed by his works;
23and the Scripture was fulfilled that says, “Abraham believed God, and it was counted to him as righteousness”—and he was called a friend of God.
24You see that a person is justified by works and not by faith alone.
25And in the same way was not also Rahab the prostitute justified by works when she received the messengers and sent them out by another way?
26For as the body apart from the spirit is dead, so also faith apart from works is dead.
So we see from reading the whole passage in its proper context that the point isn't that works can save, but that faith, which saves, is made evident by works. That is, that we are saved unto good works, not by good works, just as Ephesians 2:8-10 says.
In fact, the verse just before the one you cherry picked states that Abraham was justified by his faith in God.
Yeah, we know. That's why Jesus bore our sins and imputed His righteousness to us.
But Christ has made us clean.
Because you deny the sufficiency of Christ's atonement.
Catholics believe Purgatory is some mythical land where sinners must expiate their own sin. Christians believe our "purgation" was at the cross where Jesus bore and expiated our sins.