Today is the Catholic Celebration of All Souls Day.
I am not Catholic, was not raised Catholic, so I may not completely understand what this day is all about; but from what I understand this day is meant for the remembrance of those souls who are being prepared for heaven through purgatory. The idea is that the 'faithful departed' who have not been fully cleansed because of venal sins or some such are having their final sins worked out in purgatory. This day is in remembrance of them.
To the best of my knowledge, there is no real biblical passage that proves their is such a place as purgatory. My understanding is that is a Catholic tradition more than a scriptural doctrine, although I am sure there are some scriptures that can be taken out of context to support purgatory.
The bigger issue in my mind is that the concept of purgatory weakens the power of Christ. If there are people who, while believing in Christ and trusting Him for their salvation, still are not allowed into heaven because they where not fully cleansed, that demeans the power of Christ to save the lost. It implies that there is something we must do in regards to our salvation other than have faith and that our actions after we have come to Christ can actually dull Christ's salvific work.
But because of his great love for us, God, who is rich in mercy, 5 made us alive with Christ even when we were dead in transgressions—it is by grace you have been saved. 6 And God raised us up with Christ and seated us with him in the heavenly realms in Christ Jesus, 7 in order that in the coming ages he might show the incomparable riches of his grace, expressed in his kindness to us in Christ Jesus. 8 For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God— 9 not by works, so that no one can boast.
This makes it very clear that there is nothing we do that saves us. From the perspective of making us right for heaven, our actions have no influence in our attainment of heaven.
The confusion may come in the Epistle of James, where he says "What doth it profit, my brethren, though a man say he hath faith, and have not works? can faith save him?” –James 2:14
He goes on to say "Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works.” –James 2:18
James is not saying that your works save you or even have any influence in the salvation offered by Christ. He is saying that a true faith in Christ will overflow out of a believer, causing them to go spread the message of Christ through good done to others.
That being said, All Soul's Day, in it's strictest sense, celebrate nothing. Anyone who has died in Christ attains heaven without further issue.
If we take All Soul's Day a little less literally, it is a sad day of remembering those who died without the saving power of Christ in their lives.