My two cents about your post:
I believe that there is a pre-trib rapture (aka first fruits rapture)
for the Philadelphia like Christians. This will come as an incredibly
huge shock to all CINO (Christ in Name Only) sleeping Christians.
However, they will wake up and earn their rewards through the first
3.5 years of Daniels 70th week (where the Antichrist is given full
authority), and after that there is a mid-trib rapture for ALL who
ever accepted Jesus (independent of their good or bad works). So 'once
saved always saved' is true in any case but still the first fruits
rapture is a very special gift. The main criterion seems to be
watching rather than any other specific works (but it goes without
saying that we should perform as many good works due to our Love and
thankfulness for Jesus every day). I believe that the desire to watch
is a result from our deepest love with Jesus. We are watching mainly
because we are a bride waiting for the groom. The second 3.5 years is
for the gentiles and the Jews. The Wrath of God does not start as long
as the church is here (until Mid Trib).
Some scriptures supporting this:
1) The 10 virgins: 5 are ready to go, 5 need to go to buy oil: do good
works during the first half of the tribulation to earn their rewards
in the kingdom of heaven. It is important to note that this is not a
punishment but God in his love gives them a second chance to finally
catch up with what they missed.
2) Eliah and Elisha: Just before Eliah is raptured, Elisha refuses to
talk about it! Very similar to many sleeping Christians today! But
after Eliah departs, Elisha gets the double salvation of Eliah - I
guess that's how it will be immediately after the first fruits
3) Daniel and his 3 friends: While Daniel gets into the highest
position of the Kingdom, his 3 friends are rulers over cities under
his command. When Nebuchadnezzar makes the statue, the faith of the 3
friends is tested and they have to go through the fire (but are
protected). Where is Daniel during all that? He is not even mentioned
and does not have to go through this horrible trial. So Daniel is a
type of the first fruits rapture, and his friends are types of
Christians going through the fire of tribulation.
4) Also interesting but negotiable: Enoch and Methuselah: Enoch is
raptured (first fruits?) because he pleased God. Methusaleh is dying
(type of the faithful but persecuted christian?) right before the
wrath of God starts.
5) Jesus is a type of Adam, hence it is interesting to look how Eve
was made. The whole body of Adam was sleeping (like the church
today!), while God chose a rather unimpressive part of the Body of
Adam to create his Bride! It is not the full body of Adam that became
his Bride, but only one rip!
6) In the song of Salmon (6:8 - 7:1) the selected bride is only one
(the true dove, the bride!) out of many. Suddenly (7:1) she (= The
Shulammit, which is the She-Salmon, aka, the true Bride!) is gone and
the others are crying: Come back, come back, we want to see what was
so special about you!
I believe there are many more similar indicators we could find
supporting the first fruits rapture.
I found the following article very helpful in my initial understanding
of the first fruits rapture:
Watch and pray!