While those who called themselves Muslims in this world, might fail in the hereafter on the account that they did not seriously and without any bias, seek the Truth or that even after knowing the Truth, did not submit to it or lived their lives in accordance with it. Thus, the criteria of success or failure is one that depends purely on the internal mechanism of the human soul and intellect. It is only the Omniscient God who really knows whether a person rejected after being truly convinced of the Truth or whether his rejection was because of some misunderstanding or unanswered questions, regarding that Truth. On the day of reckoning, God shall give His decision on the basis of His absolute knowledge about the reasons of the rejection of the individuals. He answers all their questions.
Truth becomes evidently distinct from falsehood.
The former are, thus, bound to be thrown in the hell fire and the latter are promised the bliss of paradise. Therefore the Jews and Christians who lived during the life of the Prophet and who did not accept his message are doomed. They shall have no excuse for their rejection. It is these Jews and Christians that are sure to be doomed. As far as the Jews and Christians of other times and places are concerned, they are subjected to the same test in the life of this world.