It must be understood that one of the basic principles of faith is referring to Allaah, may He be exalted, and His Messenger (blessings and peace of Allaah be upon him) for judgement, submitting to their ruling and being content with it. Allaah says (interpretation of the meaning):
“(And) if you differ in anything amongst yourselves, refer it to Allaah and His Messenger (صلى الله عليه وسلم), if you believe in Allaah and in the Last Day. That is better and more suitable for final determination”
“But no, by your Lord, they can have no Faith, until they make you (O Muhammad صلى الله عليه وسلم) judge in all disputes between them, and find in themselves no resistance against your decisions, and accept (them) with full submission”
“Do they then seek the judgement of (the days of) Ignorance? And who is better in judgement than Allaah for a people who have firm Faith”
Every ruling that goes against the ruling of Allaah is a ruling of ignorance (Jaahiliyyah). Allaah says (interpretation of the meaning):
“Is not Allaah the Best of judges?”
“The command (or the judgement) is for none but Allaah. He has commanded that you worship none but Him (i.e. His Monotheism); that is the (true) straight religion, but most men know not”
Thus it is clear that refusing to refer for judgement to Allaah, may He be glorified and exalted, and His Messenger (blessings and peace of Allaah be upon him), or rejecting their ruling, or believing that the ruling of someone else is better than their ruling, constitutes kufr (disbelief) and puts one beyond the pale of Islam.