Among the requirements of believing in Allaah, the Exalted, and worshipping Him is submitting to His judgment, and contentment with His laws, and the referral to His book and to the Sunnah of His Messenger (SAW), in disputes with regards to statements, fundamentals, litigation's, blood, properties, and the rest of rights. For Allaah is the ultimate Judge and judgment ultimately pertains to Him. It is incumbent upon the rulers to rule by what Allah revealed, and it is incumbent upon the subjects to seek judgment from the Book of Allaah and the Sunnah of His Messenger (SAW).
With regards to rulers, Allaah says: "Verily, Allaah commands you to deliver the trust committed to you to their due owners, and that when you judge between people, to judge with justice."(4:58)
And surely excellent is that with which Allaah admonishes you. Allaah is all-Hearing, all-Seeing.
And with regards to the subjects, He said: "O you who believe, obey Allaah and obey His Messenger, and the people in authority among you. And if you dispute over anything, refer it to Allaah and His Messenger if you really believe in Allaah and the Last Day, that is best in terms of consequences." (4:59)
Then Allaah has made it clear that having faith does not conform with seeking judgment in other than what Allaah revealed. Allaah, the Exalted, says: "Do you not see those who allege to believe in what is revealed to you and what was revealed before you? They desire to seek judgment from the Taghat, although they are commanded to disbelieve in it, and Satan desires to lead them far astray." (4:60)
Then how will they fare when an affliction befalls them because of what they have achieved (of evil deeds) then they come to you swearing by Allah, saying, 'We meant nothing but the doing good and reconciliation? It is those whose secrets Allaah knows well. So turn away from them and admonish them and give them effective exhortation concerning their insights. And We have sent no Messenger but that he should be obeyed by the command of Allaah. And had they come to you when they wronged themselves, and asked forgiveness of Allah, and the Messenger also asked forgiveness for them, they would have found Allaah oft-Returning, Merciful.
"But nay, by your Rubb, they will never become believers until they set you a judge in their disputes and then find no straits in themselves concerning what your verdict, and submit with full submission." (4:65)
Allaah, the Exalted, emphasizes by oath the lack of iman of those who do not refer their disputes to the Messenger of Allaah (SWT) and be content with his judgement submissively.
Allah also ruled that those rulers who do not rule by what Allaah sent down are unbelievers, wrongdoers, and rebellious. He says: "And he who does not rule by what Allaah sent down, it is they who are the disbelievers." (5:44) And He says: "And he who does not rule by what Allaah sent down, it is they who are the wrongdoers." (5:45) And He says: "And he who does not rule by what Allaah sent down, it is they who are the rebellious." (5:47)
It is incumbent to rule by what Allaah revealed and to seek His judgment in all cases of dispute with regards to scholars opinions to accept only those opinions or statements that are substantiated by the Book and the Sunnah without taking side of a certain jurisprudential school, or certain Imam. This must apply to all litigation and rights, not just personal statutes as practiced in some countries that are related to Islam. For Islam is one entity which is indivisible. Allaah says: "O you who believe! uphold Islam in its entity (as a whole)." (2:208)
And Allah condemned the Jews saying: "Do you, then, believe in part of the Book and disbelieve in part?" (2:85)
The adherents of Madh'hab (Jurisprudential schools) must also refer the statements of their Imams to the Book and the Sunnah to accept only those of them that are in conformity with these two sources, and reject the rest, without prejudice or bias, particularly in matters of Aqeedah. The Imams, may Allaah be merciful to them, recommended doing so strongly; and this is the real Madh'hab of all the Imams. Therefore, he who opposes them is not considered as their adherent, even if he claims to be so. Rather, he would be one of those of whom Allaah says: "They take their priests and monks, and the Messiah, son of Maryam, as lords aside from Allaah." (9:31)
The above Ayah is not restricted to Christians only, rather, it applies to anyone who copies them. He who disobeys the command of Allaah and His Messenger (SAW) ruling by other than what Allaah revealed, or requests doing so following his whims, and what he loves, he would have apostatized by departing from Islam and disposing of Imaan, even if he claims to be a believer. Allaah, the Exalted, denied such people's claim to Imaan, by using the verb, 'allege' in the above-mentioned Ayah; a verb which is usually applied to those whose action and behavior belie their claims. This is proven by the words of Allaah: "And they are commanded to denounce the Taghoot." (4:60)
Because denouncing Taghoot (i.e., whatever is worshipped or obeyed beside, or aside from Allaah) is a pillar of Tawheed (the belief in the Oneness of Allah.) If man does not fulfill this pillar he would not be considered as a believer in the Oneness of Allaah, for Tawheed is the foundation of Imaan through which all good deeds are rendered sound, and without which they would be nullified. Seeking judgement from the Taghoot means believing in it [Muhammad b. Abdul Wahhab, Fath al-Majeed, p. 467-468] Allaah says: "He who disbelieves in Taghoot and believes in Allah has surely grasped a strong handle." (2:256)
Negating Imaan from him who does not rule by what Allaah revealed indicates that applying the laws of Allah is a matter of faith, creed and worship which a Muslim must uphold and adhere to. The laws of Allaah should not be applied only because they are better for people and their safety and security, rather because applying them is an act of worship.
Some people emphasize this point only and ignore the terms of faith, creed and worship of applying the Divine laws. Allaah, glory be to Him, condemns those who apply His laws for personal interest, not because they believe that applying them is an act of worship. Allaah, the Exalted, says: "And when they are summoned to Allaah and His Messenger to judge between them, behold! a party of them turn away. But if the right is in their favor, they come to him submissively." (24:48-49)
They in fact care only about what they desire, while they turn away from anything else which opposes their desires, because they do not consider as an act of worship seeking the judgement of the Messenger of Allaah (SWT) (by going to him during his lifetime and referring to his Sunnah after his death).