As mentioned above, the enemies of Islam had succeeded in circulating such anti-Qur'an traditions in the Muslim world, attributing them to famous personalities of Islam, the companions of the Prophet as well as his Ahlul bayt; and gradually the Muslims unwittingly accepted and recorded these weak, rather forged, ahadith in their collections of ahadith. In spite of that, the Muslim 'ulama', Shi'a and Sunni alike, did not believe that there was any alteration in, addition to, or omission from the Qur'an. No sensible 'alim of either sect accused the other sect that it believed in tahrif of the Qur'an.
Of course there have appeared from time to time some 'ulama' on both sides, who indulged in mudslinging against the opposite sect, not realizing that presence of a hadith in a book does not necessarily mean that the people of that group really believed in it. But such traditions remained more or less buried in the books and usually they were not propagated for the simple reason that nobody based his belief on them.
Things abruptly changed in February 1979, when the Iranian nation, under the unparalleled guidance of the late Ayatullah al-'uzma al-Khomeini succeeded in establishing the first truly Islamic government on the earth, centuries after the days of the Imams (a.s.).
Had the Iranian Revolution resulted in a satellite government following the line of the Western or the Eastern ideology, it would have been gladly accepted-or at least, tolerated-by the self-appointed Guardians of "democracy". But, contrary to the conventional wisdom, it chose to follow the line of Islam. Then it raised the slogan of Islamic Unity. By standing against all un-Islamic "isms", and not bowing before anyone except Allah, Ayatullah al-'uzma al-Khomeini and the Iranian leadership gained unsurpassed popularity in the Muslim ummah throughout the world, from Morocco to the Philippines and from Europe to Americas. Down-trodden masses saw with their own eyes that unarmed bare hands had defeated the mightiest war machine in the Middle East. It gave a new heart to the oppressed people even in non-Muslim countries like South Africa. This rapidly spreading influence of 'Khomeinism' alarmed the U.S.A., the paramount chief' of the Western 'tribes'. They started fighting against Iran, through the proxy war, through news media and in political fora.
On another front, they made their clients in Saudi Arabia and Kuwait
believe that the call of Islamic Unity was a mortal danger to their crowns.
Ordered by their masters, the Wahhabis started an intensely hateful propaganda
against 'Khomeinism', Iran and Shi'ism. Hired pens began churning out books,
articles and tracts against the Shi'as, saying that the Shi'a were kafir,
they were mushrik, they had their separate Qur'an, and believed
this Qur'an of the Muslims to be altered and incomplete. Some of their
top employees were Ihsan Ilahi Zaheer and Balighuddeen in Pakistan and
Manzoor Ahmad Nu'mani and Abul Hasan 'Ali Nadwi 
in India. The last-named case is interesting. Long before the Revolution,
he posed as a champion of the Islamic Unity. He is the Chairman of the
Muslim Personal Law Board in India with a Shi'a 'alim as his vice-chairman.
But he is also a recipient of the 'Faisal Award' of the Saudi dynasty.
And no sooner was the slogan of "Neither East nor West, Islam is the Best"
'exported' from Iran, than he aligned himself with anti-unity forces. He
has written in one of his anti-Shi' a booklets that the Shi'as do not believe
in the Qur'an, that is why there was no hafiz-e-Qur'an in the Shi'as.
He goes on writing that once when he was invited to Iran, the group was
taken to Qum where they visited the house of a Grand Ayatullah. The programme
was to start with the recital of the Qur'an, and the son of the Grand Ayatulah,
himself an 'alim, stood up, opened the Qur'an and recited some verses from
it. Then he says: "In our Sunni faith, even a child memorizes one or two
small surahs, but that Shi'a 'alim could not remember even
that much. It was because the Shi'as do not believe in the Qur'an."
Could anyone expect such childish arguments from such a great person? But it seems that the sound coming from his mouth is 'his master's voice' and the Zionism's dagger dipped in Muslims' blood is used for his pen.
A book written by such agents might be written in Urdu, Arabic or any other language; but within a few months it is translated in all major languages of the Muslim world, and made available everywhere as well as freely distributed to the hujjaj.
Ostensibly, the agents of American Islam are doing it to weaken Iran and prevent the Iranian Revolution from influencing the "Muslim Youths" as Abul Hasan Ali Nadvi himself has admitted in the preface of a book. But is this the actual motive of their Masters-the Judeo-Christian enemies of Islam? Obviously, not. The manipulators of the American Islam have exhumed some Shi'a traditions of tahrif buried in the books, with the sole aim that the Shi'a would retaliate by publicising the similar traditions found in the Sunni books, and thus the validity of the Qur'an would be questioned, Muslims' faith in this Last Divine Revelation would be destroyed and as a result. Islam would lose its power.
One of the Shi'a 'alims, Mirza Husayn Nuri (d. 1320 AH) had written a book, Faslu 'l-Khitab, in which he had first collected all the traditions of tahrif from the Sunni sources, then all the traditions from the Shi'a sources, then drawn his own conclusions which were against the accepted Shi'a belief. No sooner was the book printed than its rebuttal was written; and the book, discredited, remained forgotten and almost unknown even in the Shi'a academic circles. Now, the American Islam has reprinted Faslu 'l-Khitab, but after removing the chapter of the Sunni ahadith. They propagate that it is "an authentic Shi'a book" which proves that the Shi'a have no faith in the Qur'an. If these people were really honest, they should have printed the whole book; then their Masters would have been able to "prove" that the entire Muslim ummah did not believe in this Qur'an!!
This demeaning polemics will provide the Christian missionaries with effective arms and ammunitions to shake and rattle the Muslims' faith in the Qur'an. They hope that in this way many Muslims would easily be persuaded to embrace Christianity, and even those who would not convert, would not remain truly Muslim, nor would they follow a Book whose authenticity was doubtful.
Gladstone is reported to have once stood up in the British Parliament with a copy of the Qur'an in his hand; and declared that as long as the Muslims followed this Book, the British could not subjugate them. He advised his people to use every subterfuge to shake the Muslims' belief in the Qur'an.
That strategy of kufr had succeeded in Turkey, Egypt, Tunis, Algeria and many other so-called Muslim countries where a special breed of Muslims has been created which seems to be allergic to Islam and the Qur'an. It was about to succeed in Iran, thanks to the Pahlavi regime. But the plan failed because of the religious leaders under the guidance of the late Ayatullah al-'uzma Khomeini and because of the religiosity of the Iranian nation. Now the enemies of Islam are using this propaganda of tahrif to achieve that goal.
This is what they have planned. But Allah, subhanahu wa ta'ala, says:
They desire to put out the light of Allah with their mouth, and Allah will surely perfect His light, though the unbelievers may be averse. (61:8)