The belief in the Next Life is an essential part of faith.. there should be a certainty about the Next Life or else man is not considered a believer.
So the believer believes a certain belief about the Next Life, while the disbeliever denies or doubts about the Next Life.
It means: there will be requital and rewarding: there will be prosperity and suffering: there will be recompensing of the deeds and belief during the life of the World: such rewarding and reprisal will be in the Next Life.
It is a distinguishing mark between the believer who is certainly sure about the Next Life, and the unbeliever who denies or doubts about the Next Life: because he does not believe in God or He associates others with God, like the idols and the prophets or saints.
In fact, God let Satan of the Devil suggest and deceive man: only to know is man a believer in the Next Life or he doubts about it:
Quran 34, 21, which means:
(Yet [Iblies or Satan] had no authority over them, but only that We would know [and distinguish] the one believing in the Next Life from the one doubting about it; surely your Lord [O Mohammed] is All-Observing of everything.)
quran-ayat.com/pret/34.htm#a34_21
So the believer believes a certain belief about the Next Life, while the disbeliever denies or doubts about the Next Life.
It means: there will be requital and rewarding: there will be prosperity and suffering: there will be recompensing of the deeds and belief during the life of the World: such rewarding and reprisal will be in the Next Life.
It is a distinguishing mark between the believer who is certainly sure about the Next Life, and the unbeliever who denies or doubts about the Next Life: because he does not believe in God or He associates others with God, like the idols and the prophets or saints.
In fact, God let Satan of the Devil suggest and deceive man: only to know is man a believer in the Next Life or he doubts about it:
Quran 34, 21, which means:
(Yet [Iblies or Satan] had no authority over them, but only that We would know [and distinguish] the one believing in the Next Life from the one doubting about it; surely your Lord [O Mohammed] is All-Observing of everything.)
quran-ayat.com/pret/34.htm#a34_21