When this ultimate purpose of the Satan is considered, it becomes more comprehensible how a man goes astray when he does not render thanks to Allah. Gratefulness is a part of the test by Allah. Man is surely endowed with favor from Him and is informed about how he should benefit from all this favor. In return, he is expected to assume a submissive attitude towards his Creator. As the verses suggest, the choice of a person in this world, namely being grateful or ungrateful, is explicitly a clear sign of his faith or disbelief.
Gratefulness is also closely related to the punishment in the Hereafter.
But if you show ingratitude, truly My punishment is terrible indeed. Allah gives Glad Tidings to His Servants who believe and do righteous deeds. As this verse suggests, let alone counting up the favors of Allah, it not conceivable to categorize them. Since there is no limit to the favors of Allah, a believer should unceasingly keep himself occupied with the remembrance of Allah and express his gratefulness to Him. In expectation of some grand favor, some people wait for special occasions to render their thanks to Allah.