It is not Part of Allah's Decree to compel Belief

Allah said:

وَلَوْ شَآءَ رَبُّكَ

In the seventh verse (98), the heedless deniers of truth have been admonished for their failure to make the optimum use of the time of life allowed to them. There was still time for them to leave denial and contumacy. Otherwise, an ominous time was due to come when they will make Taubah but their Taubah will not be accepted. They will say that they believed but their belief will not be welcome. And that time will be the time when the punishment of the Hereafter will appear right before their eyes at the time of death. It was in this connection that an event relating to Sayyidna Yunus (علیہ السلام) and his people was mentioned - that has good counsels and great lessons in it.

It has been asked in this verse that the people who denied truth could have believed at a time when their believing would have been of benefit to them. It means that there was no use for it at the hour of death, or the punishment, or after being neck deep in it, or at the time Doomsday sets in for the doors of repentance will then be closed and no repentance or belief from anyone will be acceptable. Now that they still had the time, they could put their contumacy aside and become believers very much like the people of Prophet Yunus (علیہ السلام) did. When they, much before the worse happened, saw the Divine punishment coming, they lost no time, repented and believed. For this reason, Allah Ta` ala removed the painful punishment from them.