A Wahhabi contributor mentioned that Shia believe Quran is not complete. My answer to this matter is: "Glory to (Allah), this is a big slander! (Quran 24:16)."

Shias do NOT believe that Quran is missing something. There are few weak traditions which * might * imply to the contrary. Such reports are rejected and unacceptable if they want to imply such a thing.

It is interesting to point out that there are numerous traditions reported in Sahih al-Bukhari and Sahih Muslim which allege that many verses of Quran are missing. Not only that, but also they these Sunni reports allege that two chapters from the Quran are missing one of them was similar to chapter 9 (al-Bara'ah) in length!!! Some Sunni traditions even claim that the Chapter al-Ahzab (Ch. 33) was as lengthy as the Chapter of Cow (Ch. 2)!!! The Chapter of Cow is the biggest Chapter of the present Quran. The traditions inside Sahih al-Bukhari and Muslim even present some of the missing verses. (Some of these traditions will be mentioned in the following articles with full references.). Yet, fortunately Shia never accuse the Sunni brothers and sisters of believing that the Quran is incomplete. We say that either these Sunni reports are either weak or fabricated.
The completeness of Quran is so indisputable among Shia that the greatest scholar of Shia in Hadith, Abu Jafar Muhammad Ibn Ali Ibn al-Husain Ibn Babwayh, known as "Shaykh Saduq" (309/919-381/991), wrote: "Our belief is that the Quran which Allah revealed to His Prophet Muhammad is (the same as) the one between the two covers (daffatayn). And it is the one which is in the hands of the people, and is not greater in extent than that. The number of surahs as generally accepted is one hundred and fourteen ...And he who asserts that we say that it is greater in extent than that, is a liar."

Shi'i reference: Shi'ite Creed (al-I'tiqadat al-Imamiyyah), by Shaykh Saduq, English version, p77.

It should be noted that Shaykh Saduq (RA) is the greatest scholar of Hadith among the Imami Shia and was given the name of Shaykh al-Muhaddithin (i.e., the most eminent of the scholars of Hadith). And since he wrote the above in a book with the name of "The beliefs of the Imami Shia," it is quite impossible that there could be any authentic Hadith in contrary to it. It is noteworthy that Shaykh Saduq lived at the time of minor occultation of Imam Mahdi (AS) and he was one of the earliest Shia scholars. He had the honor that he was born with the prayer of Imam Mahdi (AS).

Another prominent Shia scholar is Allama Muhammad Ridha Mudhaffar who wrote in his Shia Creed book that: "We believe that the Holy Quran is revealed by Allah through the Holy Prophet of Islam dealing with every thing which is necessary for the guidance of mankind. It is an everlasting miracle of the Holy Prophet the like of which can not be produced by human mind. It excels in its eloquence, clarity, truth and knowledge. This Divine Book has not been tampered with by any one. This Holy Book which we recite today is the same Holy Quran which was revealed to the Holy Prophet. Any one who claims it to be otherwise is an evil-doer, a mere sophist, or else he is sadly mistaken. All of those who have this line of thinking have gone astray as Allah in Quran said: "Falsehood can not reach the Quran from any direction (41:42)"

- Shi'i reference: The Beliefs of Shi'ite School, by Muhammad Ridha Mudhaffar, English version, pp 50-51
Sayyid al-Murtadha, another prominent Shi'ite Scholar said: "... our certainty of the completeness of the Quran is like our certainty of the existence of countries or major events that are self evident. Motives and reasons for recording and guarding the Holy Quran are numerous. Because the Quran is a miracle of the Prophethood and the source of Islamic Knowledge and religious rule, their concern with the Quran made the Muslim Scholars highly efficient concerning grammar, its reading, and its verses."

With this various concern by the most eminent Shia scholars, there is no possibility that the Quran was added or deleted in some parts.

Besides what Allah mentioned in Quran about its protection, we can use our logic to derive the same result. Allah sent his last Messenger to show people (to the end of the time) His Right Path. Therefore if Allah does not preserve His message, He would be contradicting His own aim. Obviously, such negligence is evil according to reason. Thus, in essence, Allah preserves His message as He preserved Moses in the house of His Enemy, Pharaoh.