These great signs will be so spectacular that “there should be no cause for unbelief.” This is an unusual situation, for agency usually requires that there be the free option of belief. How is it that this portent will be so great that “there should be no cause for unbelief.” Does this not violate agency?
In this case, it creates a terrible agency. For those who believe, their belief will be confirmed. Verse 29, however, suggests that there will be unbelievers still. How could they not believe? The events that are described are tremendous, but associated with natural phenomenon. For the unbeliever who will not see the coincidence of the events and the prophecies, they will ascribe those signs to other reasons, and they will continue to disbelieve. That unbelief in the face of such a powerful sign will “bring upon themselves their own condemnation.” This is a terrible agency because it is a winnowing agency. It will confirm and save those who believe, and it will condemn and destroy those who do not.