Islam is NOT a religion for just the Arabs, it is a religion for the whole world. Based on this Islam equates all mankind. NO ONE is superior to others. God says in the Holy Quran: "We sent thee not save as a mercy for the peoples." (21:107)
And in another verse God says: "O mankind! Lo! We have created you from male and female, and have made you nations and tribes that ye may know one another. Lo! the noblest of you, in the sight of Allah, is the best in conduct. Lo! Allah is Knower, Aware." (49:13)
In his last sermon, Prophet Muhammad, peace and blessings be upon him, said: "O people! Your Lord is one Lord, and you all share the same father. There is no preference for Arabs over non-Arabs, nor for non-Arabs over Arabs. Neither is their preference for white people over black people, nor for black people over white people. Preference is only through righteousness." Then he said: "Have I conveyed the message?" and the people declared that he had. [Musnad Ahmad (22391)]
Based on this we conclude that:
1- According to Islam NO ONE is allowed to judge ANY ONE's belief because only GOD is allowed to judge. God says in the Holy Quran: "Lo! those who believe (this revelation), and those who are Jews, and the Sabaeans and the Christians and the Magians and the idolaters - Lo! Allah will decide between them on the Day of Resurrection. Lo! Allah is Witness over all things. "(22:17). The verse CLEARLY states that Muslims are NOT allowed to judge anyone.
2- A Muslim is NOT allowed to tell (even just by words) anyone that he is not a believer and hence consider himself superior to him. You can never tell who is a better believer than who. God says in the Holy Quran: "and say not unto one who offereth you peace: "Thou art not a believer," seeking the chance profits of this life (so that ye may despoil him)." (4:94), so even the word "you are not a believer" is NOT allowed.
It is reported on the authority of Ibn 'Umar that the Messenger of Allah, may peace and blessings be upon him, said: "Any person who called his brother: "O unbeliever" (has in fact done an act by which this unbelief) would return to one of them. If it were so, as he asserted (then the unbelief of man was confirmed but if it was not true), then it returned to him (to the man who labeled it on his brother Muslim)." (Sahih Muslim, The Book of Faith:122)
This point is actually very important because nowadays we see some stupid Muslims (or claiming to be Muslims) who actually kill people just because they are NOT Muslims or even kill Muslims just because they regarded them as unbelievers.
2- Islam does not give anyone a carte-blanche to heaven. A Muslim has to work to prove himself worthy of being a Muslim as well as worthy, by God's will, of going to heaven.
1- The defamed Khawarij
The Khawarij are a sect of people who innovate and follow beliefs and practices foreign to Islam. The Khawarij used to renounce Uthman (the third Caliph of Islam) for several things and they declared their disassociation from him.
Those people were known as “Reciters” for their diligence in reciting the Quran and for their worship. Yet, they used to twist and misinterpret the Quran from its intended meanings. They used to persist on their own personal opinions, and they used to appear very strict and devout in their humility, their renouncement of worldly things, and other things.
In a very long story, After Uthman was killed, they then declared Ali (his successor, the fouth caliph) to be a disbeliever and revolted against him, so he fought them. They caused such a turmoil in the peaceful Islamic state that their era was called the great Fitna when the first civil war sparkled in the Islamic state.
Long before their appearance, Prophet Muhammad, peace and blessing be upon him, warned Muslims from them. Ahmad, Muslim, and Ibn Majah recorded a hadith from Abu Dharr who narrated that prophet Muhammad, peace and blessings be upon him, said: "There will definitely be a people after me from my nation who recite the Quran yet it will not even reach beyond their throats. They will pass through the religion as an arrow passes through a target, then they will not return back to it. They are the worst of people, the worst of all creatures."
Notice that they seemed like devout Muslims, but deep inside they were completely void of any real concept of Islam. Imam Ahmad, Ibn Majah, and al-hakim recorded a hadith from Ibn Abi Awfa, and Ahmad and al-Hakim also recorded it from Abu Umamah that the prophet, peace and blessings be upon him, said:" The Khawarij are the dogs of Hell ".
So Islam did not give them a free license to heaven just because they claim to be Muslims, of course not, prophet Muhammed, peace and blessings be upon him, said that they will go to hell.
Ali Ibn Abi Talib (the fourth righteous caliph), may Allah be pleased with him when he faced them and they claimed they want nothing but for Islamic rulings to be applied and they even quoted a verse from the quran saying: "There is no rule but for Allah." (12:40) . He then told them his famous quote: "A word of truth by which is intended falsehood. "
2- Grand Mosque seizure
The Grand Mosque Seizure on November 20, 1979, was an armed attack and takeover by armed extremist insurgents of the Al-Masjid al-Haram in Mecca, Saudi Arabia, the holiest place in Islam. The insurgents declared that the Mahdi, or redeemer of Islam, had arrived in the form of one of the insurgents' leaders, Abdullah Hamid Mohammed Al-Qahtani and called on Muslims to obey him. The seizure shocked the Islamic world as hundreds of pilgrims present for the annual hajj were taken hostage, and hundreds of militants, security forces and hostages caught in crossfire were killed in the ensuing battles for control of the site. The siege ended two weeks after the takeover began with militants cleared from the mosque.
Notice here that the Saudi authorities fought and killed those extremist insurgents who tried to force people into obeying them. They too claimed to be devout Muslims and they too justified terrorizing and killing pilgrims and they too were despised, defamed and fought by Muslims.
1- No Muslim should consider himself superior to any one (Muslim or not).
2- Taking religion (any religion) as a cover for someone's evil intentions and trying to justify it using religion is the most despicable act of cowardice to be done.