Post tribbers feels like a spin off of works based salvation to me, they feel like they have to show their worth, earn their way by putting on their rambo gear and taking on the AC. While pre tribbers accept that we can't earn it, it's all by grace, something that we don't deserve.
first they are killed for their faith.. but then later they will take on the AC after they are resurrected.. that is the marriage supper of the Lamb.. I am convinced the following text is not talking about actual birds, but the saints that were killed for their testimony, and also that are being raptured to meet Christ in the air..
"
17Then I saw an angel standing in the sun; and he cried with a loud voice, saying to all the birds that fly in the midst of heaven, “Come and gather together for the
[h]supper of the great God,
18that you may eat the flesh of kings, the flesh of captains, the flesh of mighty men, the flesh of horses and of those who sit on them, and the flesh of all
people, free and slave, both small and great.”
19And I saw the beast, the kings of the earth, and their armies, gathered together to make war against Him who sat on the horse and against His army. 20Then the beast was captured, and with him the false prophet who worked signs in his presence, by which he deceived those who received the mark of the beast and those who worshiped his image. These two were cast alive into the lake of fire burning with brimstone. 21And the rest were killed with the sword which proceeded from the mouth of Him who sat on the horse. And all the birds were filled with their flesh." - Rev 19