The sentence "That Book has no doubt in it" raises a grammatical and exegetical problem, for the first phrase in the Arabic text reads as ذَٰلِكَ الْكِتَابُ :Dhcilikal kitab. Now, the word dhalika ذَٰلِكَ (that) is used to point out a distant thing, while the word kitab (book) obviously refers to the Holy Qur'an itself, which is present before us. So, this particular demonstrative pronoun does not seem to be appropriate to the situation. There is, however, subtle indication. The pronoun refers back to the prayer for the straight path made in the Surah Al-Fatihah, implying that the prayer has been granted and the Holy Qur'an is the answer to the request, which gives a detailed account of the straight path to those who seek guidance and are willing to follow it.
Having indicated this, the Holy Qur'an makes a claim about itself: "There is no doubt in it". There are two ways in which doubt or suspicion may arise with regard to the validity or authenticity of statement. Either the statement itself is erroneous, and thus becomes subject to doubt; or, the listener makes a mistake in understanding it. In the latter case, the statement does not really become subject to doubt, even if someone comes to suspect it out of a defective or distorted understanding - as the Holy Qur'an itself reminds us later in the same Surah: , وَاِنْ كُنْتُمْ فِىْ رَيْبٍ If you are in doubt..." (2:23). So, in spite of the doubts and objections of a thousand men of small or perverse understanding, it would still be true to say that there is no doubt in this book - either with regard to it having been revealed by Allah, or with regard to its contents.
ھُدًى لِّلْمُتَّقِيْنَ :"A guidance for the God-fearing": The Arabic word for the God-fearing is Muttaqin, derived from Taqwa which literally means "to fear, to refrain from", and in Islamic terminology it signifies fearing Allah and refraining from the transgression of His commandments. As for the Holy Qur'an being a guidance to the God-fearing, it actually means that although the Holy Qur'an provides guidance not only to mankind but to all existents in the universe, yet the special guidance which is the means of salvation in the other world is reserved for the God-fearing alone. We have already explained in the commentary on the Surah "Al-Fatihah" that there are three degrees of divine guidance - the first degree being common to the whole of mankind and even to animals etc., the second being particular to men and jinns, and the third being special to those who are close to Allah and have found His favour, the different levels of this last degree being limitless. It is the last two degrees of guidance which are intended in the verse under discussion. With regard to the second degree, the implication is that those who accept the guidance will have the hope of being elevated to the rank of the God-fearing. With reference to the third degree, the suggestion is that those who are already God-fearing may receive further and limitless guidance through the Holy Qur'an. This explanation should be sufficient to remove the objection that guidance is needed much more by those who are not God-fearing, for now we know that the specification of the God-fearing does not entail a denial of guidance to those who not possess this qualification.