I thought of a great analogy for purgatory the other day.
Picture yourself working in the havardous viruses lab at a research facility. Before you enter the chamber filled with deadly diseases, you put on a specially designed suit and step into an antechamber where you are quickly sprayed with water to make sure you bring nothing in and to help limit what can come out. That first part is a weak analogy for baptism and putting on the armor of God.
When you then exit the experimental chamber, you are sprayed down even more thoroughly and any remnants of the viruses you were studying are washed away. Consider those viruses as being sin, and the water is purgatory. We are washed free of the “bugs” we have gathered in our life so that we may peacefully enter heaven 100% pure and clean.