Part 1: For two important reasons that are rooted in Islam's holly book, Quran.
1) Surah al-Hujurat, Verse 13:
Human beings, We created you all from a male and a female, and made you into nations and tribes so that you may know one another. Verily the noblest of you in the sight of Allah is the most God-fearing of you.Surely Allah is All-Knowing, All-Aware.(49:13)
This verse can be interpreted as saying that all human beings are created as equal and they have equal rights. In the political system of an Islamic society this means all citizens must enjoy equal political rights.
2) Surah al-Bagharah, Verse 30:
Remember (when) your Lord said to the angels: "I am setting on the earth a vicegerent." The angels asked: "Will you set therein one who will cause disorder and corruption on it and shed blood, while we glorify You with Your praise (proclaim that You are absolutely free from any defect and that all praise belongs to You exclusively,) and declare that You alone are all-holy and to be worshipped as God and Lord." He said: "Surely I know what you do not know."
This verse can be interpreted as saying that god appointed man as his vicegerent (successor or representative) on earth. For the political system of an Islamic country this can be interpreted as saying that all human being have equal political responsibility as representatives of god. As such they have a political duty to participate in political decisions and the political system.
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Now if we combine the teachings of these two versus we can draw the following conclusion:
In the political system of an Islamic community all citizens must enjoy equal political rights. They also have a political responsibility as representatives of god on earth. This responsibility means that no individual can deny the political right of another person because every man and woman is a representative (vicegerent) of god. Therefore it is forbidden for an individual to oppress the political rights of others. And it is a sin for a person to allow another person to deny him or her equal political rights. The only modern political system that is compatible with such a belief system is a democratic system in which citizens enjoy equal political rights.
Part 2: WHY DEMOCRACY IS THE ONLY APPROPRIATE POLITICAL SYSTEM FOR MUSLIM COUNTRIES
In the first half of this article I explained why the verses of Quran reject non-democratic political systems and call the only political system that is compatible with Islam is a democratic system in which the political leader is elected by majority support. In this section I present a completely different set of arguments to explain why it is necessary for Islamic countries to adopt free and fair political systems.
Contemporary modern Islamic countries, particularly the countries of the Middle East, must adopt democracy because they have suffered a deeply troubling military and geopolitical humiliation at the hands of a small and powerful country called Israel. When we look that the history of the Arab-Israeli conflict we observe that the Arab countries have suffered repealed humiliating defeats at the hands of Israel ever since 1948. These repeated defeats have led to the loss of a significant amount of Arab lands (West Bank, Gaza, Golan Heights). Furthermore, these are not just Arab humiliations. The suffering of Palestinians and these military defeats have troubled all Muslims. This sense of Islamic solidarity manifests itself in mass protests that take place in many Muslim communities in support of the Palestinian rights.
I argue that the foundational factor that has made Israel so strong is its democratic political institutions. If it was not for its transparent and democratic system of governance Israel would not have been able to achieve military supremacy.
Israel relies the support of two groups of Jews: those who live inside Israel as citizens and millions of Jews in other countries, particularly in the United States and Europe. Both of these groups have played a crucial role in Israel’s survival and military strength. How does this take place? Democracy creates a sense of justice and fairness in the society which allows the people to unite against external threats despite ideological and political differences. Every citizen believes that the political system is fair and legitimate regardless of whether he or she agrees with the political leaders. This is because in a functioning democracy there is equal opportunity to participate in the political process both as a voter and as a candidate for any political office.