Ten things which nullify one’s Islaam
All praise is due to Allaah, Lord of the worlds. May peace and salutations be upon the Last Messenger of Allaah, and upon all those who follow him until the Last day. To proceed: Brother and Sister Muslim, you must be aware that there are matters which nullify your Islaam. Please be mindful of them:
1 - Associating partners with Allaah (shirk). Allaah Most High says (in the meaning ):
{Truly, whosoever sets up partners with Allaah, then Allaah has forbidden the Garden for him, and the Fire will be his abode. And for the wrongdoers there are no helpers}, [Soorah al-Maa.idah, Aayah 72].
Calling upon the dead, asking their help, or offering them gifts or sacrifices are all forms of shirk.
2 - Setting up intermediaries between oneself and Allaah, making supplication to them, asking their intercession with Allaah, and placing ones trust in them is unbelief (kufr).
3 - Anyone who does not consider the polytheists (mushrikeen) to be unbelievers, or who has doubts concerning their unbelief, or considers their way to be correct, is himself/herself an unbeliever (kaafir).
4 - Anyone who believes any guidance to be more perfect, or a decision other than the Prophets decision to be better, is an unbeliever. This applies to those who prefer the rule of Evil (Taghoot) to the Prophets rule. Some examples of this are:
(a) To believe that systems and laws made by human beings are better than the Sharee’ah of Islaam; for example, That the Islaamic system is not suitable for the twentieth century. That Islaam is the cause of the backwardness of the Muslims. Or that al-Islaam is a relationship between Allaah and the Muslim. It should not interfere in other aspects of life.
(b)To say that enforcing the punishments prescibed Allaah, such as cutting of the hand of the thief or the stoning of an adulterer, is not suitable for this day and age.
(c) To believe that it is permissible to give a rule from that which Allaah did not reveal in Islamic transactions or matters of law, punishments or other affairs. Although one may not believe such things to be superior to the Sharee’ah he in effect affirms such a stand by declaring a thing which Allaah has totally prohibited, such as adultery, drinking alcohol or usury, to be permissible. According to the consensus of the Muslims, one who declares such things to be permissible is an unbeliever (Kaafir)
5 - Anyone who hates any part of what the Messenger of Allaah [sal-Allaahu `alayhe wa sallam] has declared to be lawful has nullified his Islaam, even though he may act in accordance with it. Allaah Most High says (in the meaning):
{This is because they hate what Allaah has sent down, so he has made their deeds fruitless}, [Soorah Muhammad, Aayah 9].
6 - Anyone who ridicules any aspect of the religion of the Messenger of Allaah [sal-Allaahu `alayhe wa sallam], or any of its rewards or punishments, becomes an unbeliever. Allaah Most High says (in the meaning):
{Say: Was it Allaah, and His signs and His Messenger that you were mocking? Make no excuse; you have disbelieved after you had believed}, [Soorah at-Towbah, Aayahs 65-66].
7 - The practice of magic. Included in this, for example, is causing a rift between a husband and wife by turning his love for her into hatred, or tempting a person to do things he dislikes using black arts. One who engages in such a thing or is pleased with it is outside the fold of Islaam. Allaah Most High says (in the meaning):
{But neither of these two (angels, Haaroot and Maaroot) taught anyone (magic) till they had said, Indeed, we are a trial; then do not disbelieve}, [Soorah al-Baqarah, Aayah 102].
8 - Supporting and aiding polytheists against the Muslims. Allaah Most High says (in the meaning):
{Whoever among you who takes them as allies is surely one of them. Truly, Allaah does not guide the wrongdoers}, [Soorah al-Maa.idah, Aayah 51]
9 - Anyone who beleives that some people are permitted to deviate from the Sharee’ah of Muhammad [sal-Allaahu `alayhe wa sallam] is an unbeliever by the word of Allaah Most High (in the meaning):
{And whoever seeks a religion other than Islaam, it will not be accepted of him, and in the hereafter he will be from among the losers}, [Soorah Aal-'Imraan, Aayah 85]
10 - To turn completely away from the religion of Allaah neither learning its precepts nor acting upon it. Allaah most high says (what means):
{And who does greater wrong than he who is reminded of the revelations of his Lord and turns aside therefrom Truly, We shall exact retribution from the guilty}, [Soorah as-Sajdah, Aayah 22].
And He (Subhaanahu wa Ta’aala) also says (what means):
{But those who disbelieve turn away from that about which they are warned}.
It makes no difference whether such violations are committed as a joke, in seriousness or out of fear, except when done under compulsion (i.e. from threat of loss of life).
We seek refuge in Allaah from such deeds as entail His wrath and severe punishment.
Shaykh Ibn Baaz
Fataawa al-Mar.a
http://www.fatwa-online.com/fataawa/creed/shirk/9991120_1.htm