What is the ruling on those who say: Any government which does not rule by Allaah’s Law is non-Muslim and therefore it must be removed. They provide as evidence the saying of Allaah (which means): {The decision is only for Allaah.} [Quran 6:57]. Is this statement correct?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

The one who rules with other than what Allaah has revealed is of two kinds:

1-     To judge by other than what Allaah has revealed while denying what Allaah has revealed and making what Allaah has forbidden as lawful; this kind of person has committed major Kufr [disbelief], and is totally out of the fold of Islam.

2-     To judge by other than what Allaah has revealed while believing that it is an obligation to judge with what Allaah has revealed but because of following one's desires, he judged in a given matter with other than what Allaah has revealed while acknowledging his mistake and confessing that he is sinful, so this person commits a minor Kufr which does not take him out of the fold of Islam.

The first kind includes someone who legislates a law whereby he permits what is forbidden or forbids what is lawful, or that he is pleased with this, confirms it or obliges the people to abide by it.  

Allaah Knows best.