How do you explain purgatory to a strict Fundamentalist?
a. The vast majority of humans, even those who are generally good people, sin to greater or lesser degrees all of their lives (cf. Prov. 24:16). Therefore most humans have the stain of sin on their souls at death.
b. Nothing unclean shall enter heaven (cf. Rev. 21:27).
c. Unless the Fundamentalist is going to argue that almost no one enters heaven, something most Fundamentalists do not believe, then between death and glory there must be a cleansing from sin before entry into heaven (cf. Heb. 12:23). That cleansing is what Catholics refer to as purgatory (which comes from the verb “to purge”).
For more information, see these articles:
“Purgatory” by Catholic Answers:
“The Roots of Purgatory” by Catholic Answers:
“Purgatory: God’s Emergency Room for Sinners” by Patrick Madrid: