The Ulama have mentioned ten actions that negates Islam:*
1. Associating others deities with the worship of the One God Who has no partners.
Proof: Surely Allah does not forgive it when partners are ascribed to Him. He forgives everything except this for whomever He wishes 4-116.
2. Relying on an intermediary between oneself and Alla when seeking intercession.
3. Refusal to condemn the kufr of those who rely on other deities instead of Allah or doubting that they are disbeliever or approving of their religion is itself disbelief.
4. Belief that there is a more perfect guidance than that of the Prophet Muhammad, sallah lahu alahi wa salam, and tha there is a form of governance that is preferable to this, such as someone who prefers the rule of tyrants to that of the Prophet.
5. Dislike of any of the Revelation, even though one may act upon it, is disbelief.
Proof: This is because they dislike what Allah has revealed, so He makes their actions fruitless 47:9.
6. Disparaging any part of the deen or any aspect of reward or punishment.
Proof: Say: Was it Allah and His signs and his Messenger that you ridicule? Make no excuse. you have disbelieved after your belief. 9: 65-66
7. Practicing magic either black or white, is proof of disbelief
Proof: And they did not teach it to anyone until they had said: “Surely we are only a temptation, so do not disbelieve in the guidance of Allah. 2-102
8. Helping and assisting the disbeliever in overcoming the Muslims.
Proof: Whoever among you takes them for friends is surely of them. Surely Allah does not guide wrongdoing people. 5-51
9. Belief that is not necessary to follow the Prophet of Allah, and that it is permitted to step outside the law of Allah, as al-Khidr did when he exceeded what had been revealed to Musa. This is disbelief.
10. Wilful neglect of Allah’s deen neither learning it nor acting upon it.
Proof: And who does greater wrong than he who is reminded of the signs of his Lord, and then turns away from them. Surely We shall requite the guilty. 32-22
No distinction is made as regards these actions in terms of intention, whether a person is joking or serious or even acts out of fear. The only excuse is compulsion. These ten actions are extremely dangerous and exceedingly common. Every Muslim should beware of them and feel a real fear in his heart of even drawing near them. Imam Muhammad ibn Abdul Wahhab, Mu’alafat,5/212-214
* taken from the book Al Wala wa’l Bara, page 97,chapter 9 book #1.