"Humankind were one community, then God sent prophets as bearers of good news and as warners and revealed with them the Book with the truth that it [the Book] might judge between humankind concerning that in which they differed. And only those to whom the book was given differed concerning it, after clear proofs had been given them, through mutual hatred and rivalry." (Noble Quran 2:213)
Muslims have fallen victim to inventions against the word of God, the Quran. These inventions have distorted the way that God sent down via all the prophets. The message that God has been sending down has been the same throughout history .. Even though the Quran says in well over 15 places, that it is explained in detail (Verses 6:114 etc.) and contains a full explanation of whatever is needed by a believer (Verse 16:89) and should be enough, Kaafi, for them (Verse 29:51), and contains the complete law of God (Verse 45:18 and 42:13), as against man-made law or Shariah (Koran 42:21), "Muslims" insist that the Koran needs supplements to be understood, and lacks details. This amounts to disbelieving what God himself says in unequivocal terms in the Quran.
The Quran states explicitly that the messenger's duty was only to convey (Balagh) the message (Verse 29:18) contained in the Quran (Verse 69:44) and that the Quran was the only Wahi (revelation) given to the Prophet (S) to be conveyed to people (Verse 6:19) by testimony of God Himself. Therefore to follow the words of God in the Quran would be to follow the Messenger. Thus following God is the same as following the Messenger, who only conveyed the Quran (see Verse 4:80)
The inventions against the true words of God revealed to the messengers are the so called "Hadith" (stories about the sayings and doings of the prophets) as narrated by the writers of the Old Testament, the Gospels of Jesus (i.e. the "Hadith" about Jesus), and the various Hadith about Prophet Muhammed contained in the many "extra-Qoranic" books believed in by the Sunni and Shiia schools of thought. People have attributed these things throughout history to the messengers, whereas the messengers could never have said them given the history of the documents and the Criterion (Furqaan) of the Quran (Verse 2:185)
"Do they not consider the Quran with care, If it had been from anyone other than Allah, it would contain many discrepancies" (4:82).
Hadith are the various traditions contained in specific books, believed in by the majority of Muslims to be the sayings of the Prophet Muhammed (S). These are extra-Quranic, i.e. from outside the Qoran. They either contradict or add to the Quran. Muslims often present them as an explanation of the Quran or as an integral part of Islamic law, even though the Quran does not confirm them.
The Quran historically predates any written Hadith and there is no mention of Hadith or the Sunnah of the Prophet in what we possess as writings before the third century after the Prophet. Quran and rationality based on its principles formed the basis of religion for first century Muslims. Thus contrary to being an innovation, following the Quran alone is historically the original Islam and hadith, and other extra-Quranic literature is the innovation introduced in its written form in the 3rd century after the Prophet.
The various books of Hadith that we see in Muslim society today are the same in relation to Prophet Muhammed as the gospels are to Prophet Jesus. They are both similar in that both were complied centuries later [unlike the Koran which was memorized and written down at the time of its revelation] and they both present no proof of authenticity [unlike the Koran in which numerous verses say: "In this is a sign (or proof)" and then asks you to refute it]. Therefore, objectively speaking, both the Hadith and the gospels do not present any evidence as to be considered a 100% reliable representation of the words of the Prophets, Muhammad and Jesus. Modern scholarship of both the gospels and the Hadith finds them an unreliable representation of the words of the prophets or even their close companions.
Professor Schacht .. did not believe that the Hadith or the concept of "Sunna of the Prophet" were part of first century Islam. Shafi [150-204/767-819] introduced them, at the earliest, nearly two hundred years after the death of the Prophet. The Quran states exactly the same. The Quran was the only "Hadith" that was conveyed by the Prophet and formed the guidance for the early Muslim community.
"...If any do fail to judge by what Allah(God) has sent down (i.e the Quran), they are unbelievers (Kaafiroon)." (Verse 5:45).
"...If any do fail to judge by that which Allah has sent down, they are tyrants (dhilamoon)." (Verse 5:45)
"...If any do fail to judge by that which Allah has sent down, such are evil-livers (fasikoon)." (Verse 5:47)
The Quran reports that the messenger himself will complain to God about his so called followers abandoning the Quran:
"And the messenger says,"O my Lord, my OWN people have forsaken the Quran." (Quran 25:30)
"Is not the time ripe for the hearts of those who believe to submit to Allah's reminder and to the truth which is revealed, that they become not as those who received the scripture of old but the term was prolonged for them and so their hearts were hardened, and many of them are evil-livers." (57:16).
The scientific method demands that "subjective" proof (i.e. how truthful a person was) be ignored and the item tested on objective criteria. What does the content say?
Hadith doctors have traditionally evaluated Hadith on its chain of narrators and its body text, according to their own criteria of what should be correct. However even according to their own standards, they fell into a dilemma. Some Hadith exist which have according to them a "sound" chain of narrators but they dispute the text of the Hadith. One example of this and their whole system collapses. The Quran gives us the standard for judging anything that is presented. If the Quran confirms it in total, its true. If the material adds to or contradicts the Quran, its source is not God nor His messenger.