I like Gebre Menfes's reply (and alejkëm selam
, of course). Having been away for several days and read the whole thread in one go, I am not replying much to individual points with quotations, but I would like to add a few observations.
The thread seems to have bifurcated: one question is the origin of the Premillennial, pre-Tribulation Rapture understanding of eschatology. I think that has been answered and explained well in a number of posts. The other question is how to cope with people who (to use Rosehip's word) brag about their blessings in the ways she has described. This is a much more difficult question. (I assume you are concluding from your experience that it is Pre-Mill people who thus brag, but I wonder whether this might be a false link.)
First, let me say that, over the past 20 years in my work with the Albanian Mission, I have moved amongst Evangelicals in Scotland, England, Wales, France, Greece, Albania, Kosova, Germany and the Republic of Macedonia, and among various shades of Evangelicals - Baptists, Methodists, Anglicans, Brethren, Pentecostal and others - and I have seldom come across the problem you so painfully describe. We had one preacher who occasionally came to our Baptist church in Wrexham whilst we were between pastors, who might be seen as a mild example of the type you describe: he is Pentecostal, and he stopped being invited but not (I think) because he was Pentecostal; I preached at a Pentecostal church in Yorkshire and another in Sussex, and to a muted extent in comparison with your experience I encountered it there in the homes of the people who accommodated and/or fed me. This leads me to two speculations: (1) is the problem more a national cultural one (i.e. American), and (2) does it arise mostly in Pentecostal and (their off-spring) Charismatic circles? These are questions, not answers.
But how to deal with it when it arises? Five things come to mind:
1) Most importantly, you need to be quietly confident of your own relationship with God, so that the disturbance does not reach your trusting soul.
2) 1 Peter 3 tells us to "be prepared to make a defense to anyone who calls you to account for the hope that is in you, yet do it with gentleness and reverence
". This would surely apply when we converse with those who are really challenging our relationship with Christ in comparison with their own, as they see it.
3) Jude 9 tells us that even the archangel Michael in contending with the devil "did not presume to pronounce a reviling judgement upon him," so it seems to me that we, who are "a little lower than the angels", ought not to respond with similar counter boasts or rebukes.
4) One reason for this, to my mind, is that we might just possibly, and unintentionally, fall into finding fault with something that God really has done for this person (even though he ought not to brag about it), and we would thus be found to find fault with God's handiwork.
5) Surely such people should be viewed not as non-Christians but as immature Christians whose need is to grow in grace? We learn from scripture and experience that "through much tribulation we must enter the kingdom": it seems they have not yet absorbed that lesson, and only time and God's patient and perhaps chastising work in their lives will teach it to them. Not you or I in all likelihood.
Finally - and earnestly not wishing to cause offence - it is worth noting that many of the claims which some Orthodox make against us Evangelicals do seem - or shall I rather say, could seem - like triumphalism or even like boasting. But I don't want to start corresponding about petards.