Аль Имран 3:101

This world is a place of trial. Here, man is forever exposed to Satan’s evil temptations. So there is always the possibility of Satan’s succeeding in turning one from belief to unbelief. Then, while in this state—devoid of the true spirit of faith—one’s time of departure from this world might come, making it almost impossible for one to make amends. That is why it is always necessary for man to be cautious: he must become his own keeper. The actual mainspring of religion is fear of God (taqwa), that is, adopting till one’s dying day an unshakeable sense of accountability to God for all of one’s actions. This is the true and straight path. Any turning away from this path occurs when certain parts of the religion are modified in order to change the order of priorities, e.g. what is important is relegated to a secondary place, and vice versa. Such deviation mostly occurs when some secondary aspect is taken to be a fundamental part of religion and is stressed in a manner which should be reserved for the fear of God and concern for the Hereafter. Whenever such alterations are made in a religion, it necessarily results in differences which lead to serious schisms, with one group stressing one particular secondary aspect and another group stressing another particular secondary aspect—all of which culminates in the community splitting up into a number of sects. While an attitude inspired by the fear of God (taqwa) focuses all attention on the one and only God, in the absence of such fear, it is purely trivial matters which are thrust to the forefront. When peripheral issues are thus given importance, the upshot is disunity—and this is what brings on all the evils that push man to the brink of Hell. Disunity in a group must, therefore, be eschewed at all costs, for it will lead to calamity both in this world and in the Hereafter. It must be conceded that it is only when all of the emphasis is on taqwa that unity is a natural consequence.