The Qur'an is a "Preserved" Book
As our Lord explicitly states in a verse, the Qur'an is a "preserved" Book.
It is We Who have sent down the Reminder [the Qur'an] and We Who will preserve it. (Qur'an, 15: 9)
It is impossible for some verses in a book which is "preserved" and whose commandments apply to all Muslims to be regarded as valid, while others are not. The perfection in the entirety of the Qur'an, its mathematical and scientific miracles, the fact that it is a guide and the verses regarding how it has been preserved all rebut these claims made by fanatics and some opponents of Islam.
Those who reject the Remembrance [the Qur'an] when it comes to them –truly it is a Mighty Book; falsehood cannot reach it from before it or behind it – it is a revelation from One Who is All-Wise, Praiseworthy. (Qur'an, 41:41-42)
Let us now look at where these people have gone wrong.
The Mistakes in Differentiating between the "Meccan Period Muslims" and "Medina Period Muslims"
Some opponents of Islam refer to moderate Muslims as "Meccan period Muslims." In their view, the time when our Prophet (pbuh) was in Mecca was a peaceful time of no wars, yet wars suddenly started following our Prophet's (pbuh) migration to Medina. Some people claim, on that basis, that the proponents of war in Islam recognize only the verses revealed in the Medina period, while peace-loving Muslims recognize only the verses from the Meccan period. That idea is as illogical as it is ignorant.
As we have already seen, the essential precondition for a Muslim to acquire the identity of a Muslim is to believe in all the verses of the Qur'an, without exception. If someone rejects a single verse, then he loses the attribute of being a Muslim as described in the Qur'an. There is therefore no possibility in the eyes of the Qur'an of someone who says, "I am a Muslim" to discriminate by saying, "I recognize this verse but not that one."
It is true that there was no fighting in the Meccan period in the life of our Prophet (pbuh), but that there was fighting in the Medinan period and that verses were sent down concerning those particular battles. In order to understand the reasons for this, we need to understand the difficult conditions in the time of our Prophet (pbuh).