why the necessity for Purgatory to purge us completely from sin?

Question

Isn't the the finished work on the cross sufficient?
1 John 1 v. 9 If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.

Answer 1

What does the Bible say the penalty for sin is?

Rom. 6:23: “The wages sin pays is death.”

After one’s death, is he still subject to further punishment for his sins?

Rom. 6:7: “He who has died has been acquitted from his sin.”

Answer 2

At the moment of being "saved" or baptized or whatever, a Christian is completely free from sin and if he (or she) died at that moment the he would not need purgation.

But none of us is perfect and we all occasionally sin. Some of us more than others. If we die while not in a state completely free from sin then what happens?

Catholics believe in purgation (or purgatory)

The concept of purgation is hinted at in the Bible. Here are a couple of places:

"But if someone's work is burned up, that one will suffer loss; the person will be saved, but only as through fire." 1 Cor 3:15

"So that the genuineness of your faith, more precious than gold that is perishable even though tested by fire, may prove to be for praise, glory, and honor at the revelation of Jesus Christ." 1 Pet 1:7

Are you perfect now? Most people would say no.

Will you be perfect in heaven? Most people believe yes.

Purgatory (or purgation) is the process of God's love changing our imperfect selves on earth into perfect beings in heaven. Depending on the amount of change needed by different people, this can be an easy or slightly harder process.

Everyone in purgatory is on his or her way to heaven.

I do not think Mother Teresa of Calcutta had a very hard time of it.

+ With love in Christ.