(Original Sources: http://sunnianswers.wordpress.com/2008/05/20/q-a-is-denying-well-known-things-such-as-the-hijab-kufr/ 

and

http://sunnianswers.wordpress.com/2008/05/23/q-a-is-denying-well-known-things-such-as-the-hijab-kufr-part-ii/ )

by Shaykh Abu Adam al Naruiji

Question: Is a person considered a kafir if he denies such well known things in Islam such as the obligation of the Hijab or the hadd of apostasy or believes the Islamic state to be something not ordained by Islam or mocks the Niqab?

Answer: First of all, kufr is primarily a matter of belief, a matter of what is in the heart. However, there are two aspects to this belief in the heart. The first is the belief in the sense of affirming something as true in the heart. The second is for this belief to be submitted to in the heart; completely accepted without ill feeling against it, or looking down on it. Iblis is a kaafir, not because he fails on the first part, because he knows that Islam is the correct religion, but because he fails on the second part. He first fell out of Islam because he showed disdain for an order of Allah.

Organs other than the heart, however, do have a role in matters of kufr, because they can be used to express disbelief or disdain for something that is respected in the religion. So if someone says something that is plain kufr, such as saying that Aļļaah has a son, then he falls out of Islam. This is because if he believed it true, then he has adopted a kufr belief, and if he did not believe it, then he has shown scorn toward a grave matter in the religion.

Accordingly, if someone denies or has disdain for something he knows is of the religion, then he is a kafir in Allah’s judgment. It does not make any difference whether this matter is well known among people or not. Among muslims, however, one cannot easily know whether a person knows something to be of the religion or not. That is why the scholars said that a Muslim is only considered an apostate if he denies or shows disdain for something that is well known to be of the religion even among commoners. This is because in this case one could safely assume that he knows it is of the religion. If on the other hand, he denied something that is not well known, but definitely part of the religion, such as the prohibition of shaking hands with one’s wife adult sister, then one cannot assume that this person knew this rule and denied it stubbornly. Instead he is considered sinful for having denied this prohibition. But this does not mean that the person did not commit kufr in Allah’s judgment, because he might have actually known that this prohibition is true in Islam when he denied it.

Thus, if rules, such as those you mentioned, are truly well known among people, to the extent that commoners know them as well as scholars, then we consider the one who denies them or shows disdain for them as a kafir. The exception would be a person who is isolated from the knowledge of these things, or he is new to Islam. Unfortunately, today we live in a world that most people can almost be considered like new muslims in many issues, so one must not be quick to judge.

These rules above apply for narrational beliefs, beliefs that can only be known by having heard them. They do not apply for things that have a direct impact on one’s belief in the Oneness of Allah or the prophethood of Prophet Muĥammad, such as if someone believed that Allah has a son or a partner, or that the world is eternal, or that there is more than one creator, or that Allah has physical limits, or the like. For example, At-Tahaawi said: {Whoever attributed to Allah an attribute that has a meaning among the meanings that apply to humans has committed blasphemy.} Later he mentioned examples of such meanings, and said: {Allah is above} the status of {having limits, extremes, corners, limbs or instruments}.

Another important example of such kufr is if someone denied the belief that Islam is the only correct religion, and denied that other belief systems are lowly and wrong.

Disbelief in such matters are kufr whether people know them well or not, because the pillar of the belief, the belief in Allah and His Prophet, and the belief that Islam as the only religion accepted by Allah is not there.

As for the specific narrational beliefs you asked about, you should address a qualified mufti to investigate each individual case. For example, is the person like a new muslim? Did his denial have an element of acceptance or respect for other religions (belief systems) than Islam? etc.

Question: I think I’m having trouble drawing the line between sin and kufr. If you genuinly in your heart believe something isnt that right but you go and do it anyway that makes you a sinner, but if you believe its wrong, and do the wrong then say its right, that’s kufr?

Answer: The problem is in believing that the Shariah mandates an action as wrong, but not accepting the judgment of the Shariah on that issue. This is because if you truly believed that a particular action was mandated as “wrong” by the Shariah, but outwardly said that it was not wrong to do it, then you willfully denied what you believe the Prophet to have brought to us.

Committing a sinful action, however, is not kufr if one believes it to be sinful, and has no scorn in the heart towards the rule. This is unless the action involves something that only a kafir would do, such as bowing to an idol or stepping on the Quran.

Question: All the rulings of what is haram/halal is found from the Shariah, so where is it all written down for laymen to read?

I suppose you mean the issues of what is kufr? The books of the Hanafi scholars are very detailed on this, but you can also find it other schools’ books. I do not know any good translations of such books. In any case, such issues must be learned from a qualified sheikh.