Those of you who turned their backs on the day the two armies clashed—it was Satan who made them slip for what they had done. But Allah has pardoned them. Allah is Ever-Forgiving, Lenient . (Surah Al ‘Imran, 3:155)
The Qur'an, which Allah revealed from His Sight to humanity, is the last Just Book. It still exists in its pure and uncorrupted state, for He has promised to preserve it, and He always keeps His promises. In this Book, Allah explains how to serve Him, what is allowed and what is prohibited, gives the good news that those who devote their lives to Him and strive to earn His good pleasure will enter Paradise and remain therein forever, and that those who turn their backs upon Him will enter Hell and be punished for all eternity.
Yet despite these facts, the majority of people disregard the Qur'an, and some of them never pick it up at all. Ignoring Allah's verses, they indulge in this world's pleasures and never worry about having to account for themselves after death or their next life. Ignoring the limits that He has set, they do not display the moral excellence Allah expects from them, share their possessions with others, or help them when they are in need. Furthermore, when they are called to have faith in Allah, they claim to know what they are doing. Very few of them have a genuine faith in Allah and meticulously comply with His commands.
Some reflection upon these facts can help us comprehend Allah's infinite compassion and mercy. Although unbelievers intentionally turn their faces away from the just religion and transgress the limits set by Allah, He does not punish them right away. Rather, He grants them various blessings and allows them to live in abundance. Moreover, He gives them time so that they may see the truth and return to the straight path. Islam is easy to practice, another expression of Allah's infinite mercy. In addition, He does not hold people responsible for their forgetfulness or their mistakes, and does not impose any responsibility upon the blind, the lame, and the sick. He relieves people's burdens by instructing them about patience and trust in Him. All of these examples are enough to grasp Allah's infinite mercy and compassion and the unbelievers' ungratefulness.
We need to keep another point in mind as well: Allah is infinitely just and, both in this world and the next, He will recompense people according to the best of what they did. This attribute is related in several verses, as follows:
Allah will not take you to task for inadvertent statements in your oaths, but He will take you to task for the intention your hearts have made. Allah is Ever-Forgiving, Lenient. (Surat al-Baqara, 2:225)
The seven heavens and Earth and everyone in them glorify Him. There is nothing that does not glorify Him with praise, but you do not understand their glorification. He is Lenient, Ever-Forgiving. (Surat al-Isra', 17:44)
Allah keeps a firm hold on the heavens and Earth, preventing them from vanishing. And if they vanished, no one could then keep hold of them. Certainly He is Lenient, Ever-Forgiving. (Surah Fatir, 35:41)