Quitting Islam occur when one of five matters, all of which are similar and familiar, falls. These five matters are atheism, polytheism, deviation, immorality, and commitment of the grand sins.
Atheism is every deed by which God is disobeyed due to renouncement, denial, disparagement, and underestimation, whether that deed is small or big. The doer of such deeds is atheist and bears the quality of atheism. Everyone, regardless of the religion or the sect, who commits disobedience of such characters, is atheist.
Polytheism is every act of disobedience that is committed and taken as a creed, whether small or big. The doer of such an act of disobedience is polytheist.
Deviation is the ignorance of the obligatory matters. It stands for ignoring one of the grand acts of obedience, without which faith is not materialized, despite the existence of proofs and evidence. The neglector of such an act is neither denying such acts’ being obligatory nor be taking the denial of such obligatory acts as creed. He neglects them due to laziness, inadvertence, and engagement in other affairs. He is deviant and swerving from the course of faith due to ignorance and misguidance.
Thus, he deserves the name and meaning of deviation as long as the previous description applies to him. If the doer inclines to any aspect of disobedience desirably due to denial, belittlement, and negligence, he will be regarded as atheist. If he inclines to betake his own interpretations, pursuance, submission, and acceptance of the words of the fathers and forefathers as creed, he then will be regarded as polytheist. A man that pursues a deviation will rarely get rid of the inclination whimsically to having some of the above-mentioned qualities.
Immorality is every grand act of disobedience that is committed due to appetite, lust, and pre-vailing desire. The doer of such acts is regarded as immoral and swerving from the course of faith due to his immorality. He would be regarded as atheist if he kept on such immorality until he came under the forms of negligence and belittlement.
The commitment of the grand sins that voids the faith is the engagement wholly in committing the grand acts of disobedience without denial, taking as creed, appetite, or lust, but it is only due to fanaticism and rage that makes one accuse, vilify, kill, seize fortunes, hold up rights, and commit the like grand sins that are perpetrated for reasons other than pursuance of appetite. Per-jury, usury, and the like sins that are committed for motives other than pursuing the appetite, such as consuming intoxicants, fornication, and forbidden amusement. The committer of such grand sins violates his faith and swerves from it while he is not polytheist, atheist, or deviant. He deserves the quality of ignorance if the descriptions are applied to him. If he inclines to the qualities of what we have described, the quality will attach him.