Sufi Muhammed's statement that 'Democracy is Kufr' will obviously be met with unbelievable disbelief.
But, suppose a bunch of male chauvinist, lousy-character men got into the parliament and passed a Bill in majority. The bill said that the punishment of rape is not death, as decreed by Islam, but just some pitiful fine. What would we say to such a democratic resolution?
Islam does not allow anyone to play with just and fixed society rules on the personal whims and inaccurate decision of somebody who happened to get into power.
To play with the rules of Allah Subhaan'o wa Ta'ala, is in effect to negate them. Hence, the word, Kufr, i.e. to disbelieve.
The slogan of democracy is, By the People, For the People, To the People. Not to mention the fact that it has no mention of The God Who happened to create the very people and the very minds who are today trying to devise error-free rules and regulations. However, suppose the parliament members were really selected by the people, which at least does not happen in Pakistan, for over here entire villages are sold out for vote to a single party. Then, it is natural and experience has proved that people change with time. They have a different ideology before the elections and a different outlook after the elections. What should the people do now? Run after them?
No. Majority of the governance laws relating to education, health, human rights, deployment of resources, economics and international policy are predefined by Islam and Ijtehad, called the Shariah. There will be no voting upon it. It is for the own safeguard of the public and to counter the possibility of corruption emerging into a now-elected ruler's mind.
The decision may be to choose among who can best serve as a learned, brave and capable leader, just like the rules of cricket are fixed, one just looks for the best player.