Catholicism and purgatory - Could someone from the Catholic faith explain this to me?

Keep in mind that when you use the phrase "Catholics believe ...", what you are saying is "Every Christian on earth from apostolic times until the 16th Century believed ...". What every Christian on earth believed until a few hundred years ago, and what the original and true Christian Church continues to teach until the end of time, is that each person stands before God in judgment at the moment of his/her death, and is judged as either damned or saved. Those who are damned go to hell. Those who are saved, and in a state of spiritual purity, go directly to heaven. Others who are saved are not yet spiritually pure enough to enter into the presence of God, for the Bible says "nothing unclean can come into God's presence". These saved souls undergo a period of spiritual purification in Purgatory before entering into their eternal reward.