137. The allusion is to the Jews and the Christians.
138. 'Signs of Allah' include the teachings embodied in the Qur'an. They are also manifest in the noble life of the Prophet (peace be on him), and the pure lives of those who believed in him. Tley also include the natural phenomena to which the Qur'an refers in support of its message.
139. That is, either tokens of the approach of the Day of Reckoning or God's scourge or any other sign that will uncover the Truth, after which there will be no reason left for testing man.
140. Those tokens will be so clear that after their appearance it will neither avail the unbeliever to repent of his unbelief nor the disobedient to forsake his disobedience. For faith and obedience have meaning and value only as long as the Truth remains hidden, as long as the tenure of life granted to people does not seem to have approached its end and the world with all its vanities continues to delude man that, as there may neither be God nor After-life, one should eat, drink and enjoy oneself as best one can.
141. This is addressed to the Prophet (peace be on him) and through him to all followers of the true faith. The import of this statement is that true faith has always consisted, and still consists, in recognizing the One True God as one's God and Lord; in associating none with God in His divinity - neither in respect of His essence, nor of His attributes, nor of His claims upon His creatures; in believing in the Hereafter and hence considering oneself answerable before God; and in living according to those principles and values which have been communicated by God to mankind through His Prophets and Books. This was the religion entrusted to man at the beginning of human life. The religions which emerged later stemmed from the perverted ingenuity of man, from his baser lusts, and from an exaggerated sense of devotion to venerable personalities. Such factors corrupted the original religion and overlaid it with harmful innovations. Hence, people modified and distorted the original beliefs by mixing them with products of their conjecture and philosophical thinking. More and more innovations were added to the original laws of the true religion. Putting aside the Law of God, men set themselves up as their own law-makers, indulged in hair-splitting elaborations, and exaggerated the importance of disagreements in minor legal problems. They showed excessive veneration for some Prophets of God and some standard-bearers of the true religion, and directed their rancour and hatred against the others. Thus there emerged innumerable religions and sects, the birth of each leading to the fragmentation of humanity into an ever-increasing number of mutually hostile groups. Anyone who decides to follow the true religion must therefore cut himself off from all factions and chart an independent course.