Matthew 24:41 says, "Two women will be grinding at the mill: one will be taken and the other left." This verse links with a similar illustration in Matthew 24:40. A key to understanding the Bible is to examine a verse in its context. The full context begins in Matthew 24:36 with, "But of that day and hour [of Jesus Christ's second coming] no one knows." It ends in Matthew 24:44 with, "Therefore you also be ready, for the Son of Man is coming at an hour you do not expect." Clearly, the topic is preparedness for Christ's second coming.
In the immediate context, Christ makes plain the fact that no one knows the timing of His coming, not of His "near approach," as the rapture theory would suggest. His advice to Christians, in light of this fact, is that we need to be constantly alert, always in a state of spiritual preparedness—"Watch therefore" (Matthew 24:42). The suddenness of His coming will catch people who are not prepared off guard. His return will surprise some living or working side-by-side with Christians who are ready.
But was Jesus even talking about people being caught up in the air to Him, or was He saying one would be taken and another left? Note that the people of Noah’s day “did not know until the flood came and took them all away” (verse 39). So being taken here was a bad thing—being taken in calamity and death. Likewise it would seem that those who are “taken” in the end time are those who are swept away by the swirl of catastrophic events. Those who are “left” are spared. In any case, this has nothing to do with the rapture.