Regardless of the timing of the rapture of God's people, the concept of the transition and purification of Christians during the Great Tribulation is a Protestant form of purgatory.
I believe that both the rapture before the Tribulation and the middle of the Tribulation are possible according to Scripture.
I do not believe that the "after the Tribulation" scenario is viable because there are important differences between the rapture and the second coming:
1. during the rapture, believers meet the Lord in the air ( 1 Thessalonians 4:17 ). At the second coming, believers return with the Lord to the earth ( Revelation 19:14 ).
2. the Second Coming occurs after the end of the great and terrible Tribulation ( Rev. 6-19 ). Grasping occurs before compression begins ( 1 Thessalonians 5: 9 ; Revelation 3:10 ).
3 The rapture is the removal of believers from the earth as an act of deliverance ( 1 Thessalonians 4: 13-17 , 1 Thessalonians 5: 9 ). The second coming includes the removal of unbelievers as an act of judgment ( Mt 24: 40-41 ).
4. the capture will be secret and immediate ( 1 Corinthians 15: 50-54 ). The second coming will be visible to all ( Revelation 1: 7 ; Matthew 24: 29-30 ).
