<<<The bible specifically states that those who are born again will escape
the Tribulation.>>>

  specific passage please( as I only see the Philadelphians, which is only a portion of the church, escaping in Rev 3:7,10) and look at Luke 21:36  

The bible specifically states that those who are born again will escape
the Tribulation.  Since the Holy Spirit is our guarantor of salvation,
and he is not removed until the Rapture (In believers), it is not
possible that some will be left behind to go through the Tribulation.

  Problem is you are equating salvation and rapture. The rapture is a reward for few not all. Just as the crowns will not go to all but to those who do what is required to get them so too will the rapture be for those who do Luke 21:36(watch and pray to be worthy). After all do you think God will have the Laodiceans there??? the Sardis'???? the ecumenicalists???.  While one must be saved to be raptured just because they are saved doesn't mean they will be rapture. Salvation is but one requirement of that reward. If you are left behind it is not because you aren't saved just you didn't do what was necessary for that reward( you didn't watch and pray to escape). You are still part of the bride, the bible says nothing of bridesmaids and the wedding is at the end of the tribulation not straight after the rapture. For many are called, but few [are] chosen. many are christian but few will be raptured. And remember all the virgins knew of coming of the groom but only a few did what was necessary to be prepared for him.