Well if it is the land with all the population, that could mean 90% of humanity would still die in the 4th Seal. Not sure why 25% is wrong. In the Trumpets it is 33%
My take on this is that these
two percentages are two sets of catastrophes unrelated to eachother. Death comes to 25 % of the population just from the four horsemen bringing wars, famine and pestilence. That is accumulative and overlaps the other causes of death: massive worldwide earthquake, 1/3 of the planet being on fire, super volcanic eruptions and possibly an Asteroid which both cause massive tsunamis that sink 1/3 of the sea vessels in the world and kill all coastal peoples in 1/3 of the coastal regions.100 lb. hailstones can be created by trillions of tons of water that are splashed many miles upward into the atmosphere from an asteroid striking the sea.
So by the time the Seventh Trumpet is blown, 8 billion x .25 = 2 billion die PLUS 1/3 out of the remaining 6 billion leaves 4 million. 2.7 billion Christians are taken up, leaving 1.3 billion to suffer further judgments in the Seven Bowls of wrath. God protects a remnant somehow through this but they only account for a small portion of the remaining population, maybe tens of millions. So I'm thinking around 5 billion will die. I could be wrong. ???
Maybe ... just maybe, God will be more merciful than that and after every eye sees Him, Muslims who at least accepted Jesus as a prophet but believed in a distorted view of God, (Allah) and the Koran (a false religious book), may cause them to repent, abandon their religion (a false concept of God and life as it should be) and reach out for Jesus? I scratch my head with that one but after my rebellious mother, who had a smorgasbord of false believes all her life and believed Jesus was nothing more than a good man who was crucified (not for her sins which she was adament about not having any), miraculously changed and believed in Jesus three days before she died at 86 years old! After that, my view of a much more merciful God was a pleasant surprise and relief. After 30 years of chipping away at my moms false beliefs, I about gave up - God did not. He was there all along and so with all those who have love in their hearts regardless of what they believe, God may lift their veils too. Then of course much less than 5 billion will die.
After our resurrection, will it be too late, even if they haven't taken the Mark of the Beast? ???
If many who have been on the fence about Jesus, come to the truth after the Resurrection of the Church is realized, that will be wonderful.
BUT, what happens when the Church is taken up? The Holy Spirit, The Restrainer, is taken out of the way too. This may mean that no one can be converted after such time. During the time of the Seven Bowls it appears that no one repents, but they all curse God.
So it is, as it's been for thousands of years, we just don't know for sure.