I'll post the scripture again...
2Th 2:8 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming:
2Th 2:9 Even him, whose coming is after the working of Satan with all power and signs and lying wonders,
2Th 2:10 And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.
2Th 2:11 And for this cause God shall send them strong delusion, that they should believe a lie:
2Th 2:12 That they all might be damned who believed not the truth, but had pleasure in unrighteousness.
IF you refused the grace of God before the tribulation starts, God will will send you strong delusion so that you will not accept Him after the Tribulation starts...And you will be damned...Take it or leave it...
If they are not a part of the church, why does the scripture call them saints?
Oh come on...The OT is full of saints and there's not a Christian among them...All Christians are saints...All saints are not Christians...
You take 2 Thessalonians 2:8-12 to mean that everyone living during the great tribulation "received not the love of the truth that they might be saved". It does not teach that, nor are you in a position to judge who should be damned.