Are all people resurrected at the same time?
No, all people are not resurrected at the same time. Paul writes that every man is raised in his own order, a Greek military term meaning company, battalion, or division. There will be divisions and several resurrections of believers, not all at the same moment, though close in proximity.
Les explains that all of the human race is not going to be resurrected at the same moment; there are divisions. In chapter 15, verse 23, Paul says every man in his own order, and the Greek word for order is a military term of organization—like a company, battalion, or division. So there will be several resurrections of believers, not all at the same time, but close in proximity. At the trumpet call, the dead are raised incorruptible first, and those alive are changed in a split second.