Allah said,
[قَـتِلُواْ
الَّذِينَ لاَ يُؤْمِنُونَ بِاللَّهِ وَلاَ بِالْيَوْمِ الاٌّخِرِ وَلاَ
يُحَرِّمُونَ مَا حَرَّمَ اللَّهُ وَرَسُولُهُ وَلاَ يَدِينُونَ دِينَ الْحَقِّ
مِنَ الَّذِينَ أُوتُواْ الْكِتَـبَ حَتَّى يُعْطُواْ الْجِزْيَةَ عَن يَدٍ وَهُمْ
صَـغِرُونَ ]
(Fight against those who believe not in Allah, nor in the Last Day, nor
forbid that which has been forbidden by Allah and His Messenger, and those who
acknowledge not the religion of truth among the People of the Scripture, until
they pay the Jizyah with willing submission, and feel themselves subdued.)
Therefore, when People of the Scriptures disbelieved in Muhammad , they had no
beneficial faith in any Messenger or what the Messengers brought. Rather, they
followed their religions because this conformed with their ideas, lusts and the
ways of their forefathers, not because they are Allah's Law and religion. Had
they been true believers in their religions, that faith would have directed them
to believe in Muhammad , because all Prophets gave the good news of Muhammad's
advent and commanded them to obey and follow him. Yet when he was sent, they
disbelieved in him, even though he is the mightiest of all Messengers.
Therefore, they do not follow the religion of earlier Prophets because these
religions came from Allah, but because these suit their desires and lusts.
Therefore, their claimed faith in an earlier Prophet will not benefit them
because they disbelieved in the master, the mightiest, the last and most perfect
of all Prophets . Hence Allah's statement,
[قَـتِلُواْ
الَّذِينَ لاَ يُؤْمِنُونَ بِاللَّهِ وَلاَ بِالْيَوْمِ الاٌّخِرِ وَلاَ
يُحَرِّمُونَ مَا حَرَّمَ اللَّهُ وَرَسُولُهُ وَلاَ يَدِينُونَ دِينَ الْحَقِّ
مِنَ الَّذِينَ أُوتُواْ الْكِتَـبَ]
(Fight against those who believe not in Allah, nor in the Last Day, nor
forbid that which has been forbidden by Allah and His Messenger, and those who
acknowledge not the religion of truth among the People of the Scripture,) This
honorable Ayah was revealed with the order to fight the People of the Book,
after the pagans were defeated, the people entered Allah's religion in large
numbers, and the Arabian Peninsula was secured under the Muslims' control. Allah
commanded His Messenger to fight the People of the Scriptures, Jews and
Christians, on the ninth year of Hijrah, and he prepared his army to fight the
Romans and called the people to Jihad announcing his intent and destination. The
Messenger sent his intent to various Arab areas around Al-Madinah to gather
forces, and he collected an army of thirty thousand. Some people from Al-Madinah
and some hypocrites, in and around it, lagged behind, for that year was a year
of drought and intense heat. The Messenger of Allah marched, heading towards
Ash-Sham to fight the Romans until he reached Tabuk, where he set camp for about
twenty days next to its water resources. He then prayed to Allah for a decision
and went back to Al-Madinah because it was a hard year and the people were weak,
as we will mention, Allah willing.