This will take several posts. Please hold off commenting until I have finished (I'll indicate that).
Part 1 - What it is
Purgatory
“early 13c., from M.L. purgatorium (St. Bernard, early 12c.), from L.L., "means of cleansing," prop. neut. of purgatorius (adj.) "purging, cleansing," from L. purgare (see purge).”
(Online Etymology Dictionary).
Purgatory is about cleansing and purification
Catholic belief
All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven.
(Catechism of the Catholic Church para 1030)
This belief in a cleansing and purification after death is not just a Catholic one but is common to Judaism, Orthodoxy and Protestantism, though the form and name may be different.
Judaism
“According to Judaism, the purifying process that a sullied soul undergoes to cleanse it from its spiritual uncleanliness is a temporary one, and is restorative in its intent, and not punitive, as many mistakenly believe. Ultimately, all Jews have portion in the World to Come, as do Righteous Gentiles, non-Jews who observe the Seven Noahide Commandments.” (http://www.chabad.org/library/articl...-teachings.htm)
The view of purgatory is still more clearly expressed in rabbinical passages, as in the teaching of the Shammaites: "In the last judgment day there shall be three classes of souls: the righteous shall at once be written down for the life everlasting; the wicked, for Gehenna; but those whose virtues and sins counterbalance one another shall go down to Gehenna and float up and down until they rise purified; for of them it is said: 'I will bring the third part into the fire and refine them as silver is refined, and try them as gold is tried' [Zech. xiii. 9.]; also, 'He [the Lord] bringeth down to Sheol and bringeth up again'" (I Sam. ii. 6). The Hillelites seem to have had no purgatory; for they said: "He who is 'plenteous in mercy' [Ex. xxxiv. 6.] inclines the balance toward mercy, and consequently the intermediates do not descend into Gehenna" (Tosef., Sanh. xiii. 3; R. H. 16b; Bacher, "Ag. Tan." i. 18). Still they also speak of an intermediate state. (PURGATORY - JewishEncyclopedia.com)
Rabbi Shammai (50 BC - AD 30), one of the two main teachers of early rabbinical Judaism, also is on record as having interpreted Zechariah 13:9 as referring to a state of purification after death. Isaiah 66:15-16 and Malachi 3:2-3 were also interpreted in rabbinic literature as referring to the purgatorial process.
Orthodoxy
Some Othodox teach Aerial Toll-Houses regarding the souls journey after its departure from the body after death.
But if souls have departed this life in faith and love, while nevertheless carrying away with themselves certain faults, whether small ones over which they have not repented at all, or great ones for which – even thought they have repented over them – they did not undertake to show fruits of repentance: such souls, we believe, must be cleansed from this kind of sin, (St. Mark of Ephesus)
(Aerial Toll-Houses - OrthodoxWiki)
St. Mark of Ephesus was the main spokesman and theologian for the Orthodox at the Council of Ferrara in 1438. He also wrote that “the souls of people who die with unforgiven minor sins will experience spiritual sufferings in the afterlife, which, however, are not divine punishments but self-inflicted consequences of these sins”
Protestantism (but see note below)
Many Protestants believe in a purification after death but they call it Glorification.
Glorification is the Protestant alternative to purgatory, as it is "the means by which the elect receive perfection before entering into the kingdom of Heaven."
The majority of Protestant denominations believe in this form of glorification, although some have alternative names.
(askdefine.com)
“Glorification involves first of all the believer's sanctification or moral perfection (2 Thessalonians 2:13-14; Hebrews 2:10-11 ), in which the believer will be made glorious, holy, and blameless (Ephesians 5:27 ). The process of sanctification is at work in us now (2 Corinthians 3:18 ) but moves from one degree of glory to another until it reaches final glory.”
(Bakers Evangelical Dictionary of Biblical Terms)
“Glorification marks the completion of Christ's work of redemption as the believer stands before God having been awakened from sin's deadly slumber, having been given a new heart and having been purified completely in soul and body.”
( Dr. James E. Bordwine – Westminster Presbyterian Church)
Covenant Theology: Glorification (Part 1)
Note:- I post this about Protestantism in the thread Purgatory True of False and TEXBOW responded:
My understanding is that the majority of Protestants who believe in Glorification understands that the process ends at death. That the Sanctification or Glorification is a maturing in Christ while on earth before death.
This leaves open the question- what happens if a soul is not fully sanctified and Glorified be before he/she dies?
Part 1 - What it is
Purgatory
“early 13c., from M.L. purgatorium (St. Bernard, early 12c.), from L.L., "means of cleansing," prop. neut. of purgatorius (adj.) "purging, cleansing," from L. purgare (see purge).”
(Online Etymology Dictionary).
Purgatory is about cleansing and purification
Catholic belief
All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven.
(Catechism of the Catholic Church para 1030)
This belief in a cleansing and purification after death is not just a Catholic one but is common to Judaism, Orthodoxy and Protestantism, though the form and name may be different.
Judaism
“According to Judaism, the purifying process that a sullied soul undergoes to cleanse it from its spiritual uncleanliness is a temporary one, and is restorative in its intent, and not punitive, as many mistakenly believe. Ultimately, all Jews have portion in the World to Come, as do Righteous Gentiles, non-Jews who observe the Seven Noahide Commandments.” (http://www.chabad.org/library/articl...-teachings.htm)
The view of purgatory is still more clearly expressed in rabbinical passages, as in the teaching of the Shammaites: "In the last judgment day there shall be three classes of souls: the righteous shall at once be written down for the life everlasting; the wicked, for Gehenna; but those whose virtues and sins counterbalance one another shall go down to Gehenna and float up and down until they rise purified; for of them it is said: 'I will bring the third part into the fire and refine them as silver is refined, and try them as gold is tried' [Zech. xiii. 9.]; also, 'He [the Lord] bringeth down to Sheol and bringeth up again'" (I Sam. ii. 6). The Hillelites seem to have had no purgatory; for they said: "He who is 'plenteous in mercy' [Ex. xxxiv. 6.] inclines the balance toward mercy, and consequently the intermediates do not descend into Gehenna" (Tosef., Sanh. xiii. 3; R. H. 16b; Bacher, "Ag. Tan." i. 18). Still they also speak of an intermediate state. (PURGATORY - JewishEncyclopedia.com)
Rabbi Shammai (50 BC - AD 30), one of the two main teachers of early rabbinical Judaism, also is on record as having interpreted Zechariah 13:9 as referring to a state of purification after death. Isaiah 66:15-16 and Malachi 3:2-3 were also interpreted in rabbinic literature as referring to the purgatorial process.
Orthodoxy
Some Othodox teach Aerial Toll-Houses regarding the souls journey after its departure from the body after death.
But if souls have departed this life in faith and love, while nevertheless carrying away with themselves certain faults, whether small ones over which they have not repented at all, or great ones for which – even thought they have repented over them – they did not undertake to show fruits of repentance: such souls, we believe, must be cleansed from this kind of sin, (St. Mark of Ephesus)
(Aerial Toll-Houses - OrthodoxWiki)
St. Mark of Ephesus was the main spokesman and theologian for the Orthodox at the Council of Ferrara in 1438. He also wrote that “the souls of people who die with unforgiven minor sins will experience spiritual sufferings in the afterlife, which, however, are not divine punishments but self-inflicted consequences of these sins”
Protestantism (but see note below)
Many Protestants believe in a purification after death but they call it Glorification.
Glorification is the Protestant alternative to purgatory, as it is "the means by which the elect receive perfection before entering into the kingdom of Heaven."
The majority of Protestant denominations believe in this form of glorification, although some have alternative names.
(askdefine.com)
“Glorification involves first of all the believer's sanctification or moral perfection (2 Thessalonians 2:13-14; Hebrews 2:10-11 ), in which the believer will be made glorious, holy, and blameless (Ephesians 5:27 ). The process of sanctification is at work in us now (2 Corinthians 3:18 ) but moves from one degree of glory to another until it reaches final glory.”
(Bakers Evangelical Dictionary of Biblical Terms)
“Glorification marks the completion of Christ's work of redemption as the believer stands before God having been awakened from sin's deadly slumber, having been given a new heart and having been purified completely in soul and body.”
( Dr. James E. Bordwine – Westminster Presbyterian Church)
Covenant Theology: Glorification (Part 1)
Note:- I post this about Protestantism in the thread Purgatory True of False and TEXBOW responded:
My understanding is that the majority of Protestants who believe in Glorification understands that the process ends at death. That the Sanctification or Glorification is a maturing in Christ while on earth before death.
This leaves open the question- what happens if a soul is not fully sanctified and Glorified be before he/she dies?