All praise is due to Allah Alone. Peace and blessings be upon the Last Prophet, his family, Companions and those who follow his guidance.
A Muslim should know that Allah (may He be Praised) enjoins all the creation to embrace Islam, hold it firmly and avoid what contradicts it. Allah sent His Prophet Muhammad (peace be upon him) to call for that, informing them that whoever follows him will be guided and whoever turns away from him will be misguided. In many Ayahs (Qur’anic verses), Allah warned people against causes of apostasy and all forms of Shirk (associating others with Allah in His Divinity or worship) and Kufr (disbelief). Under the topic of the rulings of the apostate, scholars (may Allah be merciful with them) mentioned that a Muslim may abandon Islam by committing one of the nullifiers that make his blood and money violable and turn him out of the fold of Islam. The most dangerous and common ten nullifiers are mentioned by Shaykh and Imam Muhammad ibn `Abdul-Wahhab and other scholars (may Allah be merciful with them). Here we will list them in brief so that a Muslim can keep away from them and warn people against them in hope for safety and wellbeing. We will briefly elaborate on them.
First: Shirk in the worship of Allah. Allah (Exalted be He) says: Verily, Allâh forgives not that partners should be set up with Him (in worship), but He forgives except that (anything else) to whom He wills He (Exalted be He) also says: Verily, whosoever sets up partners (in worship) with Allâh, then Allâh has forbidden Paradise to him, and the Fire will be his abode. And for the Zâlimûn (polytheists and wrong-doers) there are no helpers. This includes invoking the dead and seeking relief, vowing or offering sacrifice for them.
Second: Whoever takes intermediaries between him and Allah, invokes, and asks them for intercession with Allah and puts his trust in them has committed Kufr (disbelief) according to the Ijma` (consensus) of scholars.
Third: Whoever does not hold the polytheists to be disbelievers, has doubts about their disbelief or considers their ways and beliefs to be correct has committed disbelief.
Fourth: Whoever believes that some guidance other than that of the Prophet (peace be upon him) is more complete than his guidance or that someone else’s judgment is better than his judgment, such as those who prefer the judgment of the Taghut (false gods) over his judgment, then he is a disbeliever.
Fifth: Whoever hates something that the Messenger (peace be upon him) came with, even though he may act on it, has disbelieved. Allah (Exalted be He) says: That is because they hate that which Allâh has sent down (this Qur’ân and Islâmic laws, etc.); so He has made their deeds fruitless.
Sixth: Whoever mocks or ridicules any part of the Messenger’s religion, its rewards or punishments has committed an act of disbelief. Allah (Exalted be He) says: Say: “Was it at Allâh (عز وجل), and His Ayât (proofs, evidence, verses, lessons, signs, revelations) and His Messenger (صلى الله عليه وسلم) that you were mocking?” Make no excuse; you disbelieved after you had believed.
Seventh: Sorcery, which includes magic spells that cause a person to hate or love someone/something. Whoever practices it or is pleased with it commits disbelief. The proof for this is the saying of Allah (Exalted be He): but neither of these two (angels) taught anyone (such things) till they had said, “We are only for trial, so disbelieve not (by learning this magic from us).”
Eighth: Supporting and assisting the polytheists against the Muslims. The proof for this is the saying of Allah (Exalted be He): And if any amongst you takes them as Auliyâ’, then surely he is one of them. Verily, Allâh guides not those people who are the Zâlimûn (polytheists and wrong-doers and unjust).
Ninth: Whoever believes that it is permitted for some people to be free of (implementing) the Shari`ah (Islamic law) brought with Muhammad (peace be upon him), then he is a disbeliever. Allah (Exalted be He) says: And whoever seeks a religion other than Islâm, it will never be accepted of him, and in the Hereafter he will be one of the losers.
Tenth: Turning away from Allah’s religion, not learning it or implementing it (is an act of disbelief). The proof for this statement is the saying of Allah: And who does more wrong than he who is reminded of the Ayât (proofs, evidence, verses, lessons, signs, revelations, etc.) of his Lord, then turns aside therefrom? Verily, We shall exact retribution from the Mujrimûn (criminals, disbelievers, polytheists, sinners).
There is no difference in committing these nullifiers between the utters them in humor, seriously, or even out of fear except for a person who says them under coercion. All of these (ten) matters are the gravest nullifiers that most often occur. A Muslim must beware of and keep away from these acts. We seek refuge with Allah from the things that entail His anger and severe punishment. May Allah’s Peace be upon the best of His Creation Muhammad, his family, and Companions!
The Fourth Nullifier includes those who believe that man-made laws and constitutions are better than the Shari`ah of Islam, equal to it, or that it is permissible to resort to them for judgment even if he believes that the judgment of Shari`ah is better. Likewise, whoever believes that it is not correct to implement the Laws of Islam in the twentieth century, that this is a cause for the fall of Muslims, or that it is limited to relationship between the servant and his Lord and should not interfere in the other affairs of life. The fourth category also includes those who hold that carrying out Allah’s laws, such as cutting off the hand of a thief or stoning a guilty adulterer is not befitting for this modern era. This category includes those who believe that it is permissible to rule by something other than the Laws of Allah (Shari’ah) in matters of transactions, Hudud (prescribed penalties) and so on, even if he does not believe that it is better than ruling by the Shari`ah. This is because, by doing that, he makes lawful that which Allah forbade, according to the consensus of scholars. Similarly, whoever makes lawful that which Allah has prohibited and this prohibition is indisputably established, such as adultery, Khamr (intoxicant), Riba (usury/interest) and ruling by anything other than the Shari`ah, then he is a disbeliever according to the consensus of Muslim scholars.
May Allah guide all of us to what pleases Him. May Allah guide us and all Muslims to His straight path! He is All-Hearer, Ever Near. May peace and blessings of Allah be upon our Prophet Muhammad, his family, and Companions!
Source for above : Shaykh Ibn Baaz – alifta.com