Surah 10. Yunus, Ayah 99

The Qur'an stresses repeatedly the fact that, "had He so willed, He would have guided you all aright" ( 6:149 ) - the obvious implication being that He has willed it otherwise: namely, that He has given man the freedom to choose between right and wrong, thus raising him to the status of a moral being (in distinction from other animals, which can only follow their instincts). See, in this context, surah {6}, note [143], as well as - in connection with the allegory of the Fall - surah {7}, note [16].

If it had been Allah's Plan or Will not to grant the limited Free-will that He has granted to man, His omnipotence could have made all mankind alike: all would then have had Faith, but that Faith would have reflected no merit on them. In the actual world as it is, man has been endowed with various faculties and capacities, so that he should strive and explore, and bring himself into harmony with Allah's Will. Hence Faith becomes a moral achievement, and to resist Faith becomes a sin. As a complementary proposition, men of Faith must not be impatient or angry if they have to contend against Unfaith, and most important of all, they must guard against the temptation of forcing Faith, i.e., imposing it on others by physical compulsion. Forced faith is no faith. They should strive.