If some Christians are left behind in the blessed hope, what's to keep them from thinking it was because they weren't saved.
That way they would misunderstand why they were left behind, and nothing would probably change.
Perhaps they would desperately make another profession of faith, thus not realizing why they were left behind.
It is not the majority of professing Christians who believe in the blessed hope anyway.
Of those that do, only a very small subset believe that some Christians will be left behind.
So there may be very little likelihood that the vast majority of Christians have ever heard that teaching.
So, if any of them are left behind, what will they be thinking?