Surah 81 The Darkening (At Takweer)
....The Surah then reminds us that it is up to every individual to choose whether to follow the right path or not. Since Allah has granted everyone his or her free will, then every human being is responsible for himself: "To those of you whose will is to be upright," this is to say, to follow Allah's guidance. All doubts have been dispelled, all excuses answered by this clear statement of all the relevant facts. The right path has been indicated for everyone who wishes to be upright. Anyone who follows a different path shall therefore, bear the responsibility for his actions.
There are, in the human soul and in the universe at large, numerous signs which beckon every man and woman to follow the path of faith.
These are so clearly visible and so powerful in their effect that one needs to make a determined effort to turn one's back on them, especially when one's attention is drawn to them in stirring, persuasive manner of the Quran.
It is, therefore, man's own will which leads him away from Allah's guidance. He has no other excuse or justification.