At that time, those among them who rejected Muhammad renounced their Islam, and those among them who followed Muhammad remained true to their Islam; as Allah Almighty has said about them: ﴿الَّذِينَ آتَيْنَاهُمُ الْكِتَابَ مِنْ قَبْلِهِ هُمْ بِهِ يُؤْمِنُونَ ۝ وَإِذَا يُتْلَى عَلَيْهِمْ قَالُوا آمَنَّا بِهِ إِنَّهُ الْحَقُّ مِنْ رَبِّنَا إِنَّا كُنَّا مِنْ قَبْلِهِ مُسْلِمِينَ ۝ أُولَئِكَ يُؤْتَوْنَ أَجْرَهُمْ مَرَّتَيْنِ بِمَا صَبَرُوا﴾[1]; “Those to whom We gave the book before it—they believe in it. And when it is recited to them, they say: ‘It is the truth from our Lord. We were Muslims before it.’ They will be given their reward twice because they remained steadfast.” Therefore, the religion of Allah is one, and all of His Prophets are like its various rulings, and all of their books are like the various verses of a single book. The necessity of following the last Prophet and Book is only due to the necessity of following the abrogating ruling and verse, which is a rational and reasonable necessity. This is the meaning of Islam.

[Islam as a Matter of Belief]

From here, it is understood that the concept of Islam is submission to the will of Allah, and that the acceptance of the last Prophet is regarded as its practical expression. However, is accepting the last Prophet in theory sufficient for the realization of the practical expression of Islam, or is accepting him in practice—through implementing the rulings conveyed by him—required? A group of Muslims, such as the Kharijites and the Salafists, hold that belief in the Prophethood of the last Prophet—meaning belief in the truth of everything he has brought from Allah and the necessity of acting upon it—is not sufficient for the realization of the practical expression of Islam, and that a Muslim is one who, in addition to this belief, adheres to its practical requirements and, specifically, refrains from deeds similar to those of disbelievers, such as seeking nearness to Allah through the dead and calling upon them. However, the truth is that this refraining—although very good and valuable—is not the practical expression of Islam, but rather that of faith, which is beyond Islam; because Islam is submission to the will of Allah in the sense of affirming His authority in theory and accepting His rulings as the means to the Muslim’s perfection, and acting upon them—which includes refraining from deeds similar to those of disbelievers—is something beyond merely affirming and accepting it;