Shaikh Rabee quotes a statement of an Imaam of the Sunnah regarding the harm of the Innovators and the fabricators of Hadeeth
Shaikh Rabee Bin Haadi Al-Madkhali (may Allaah preserve him) said:
Ibnul Jawzi said, Abul Wafaa Ibn Aqeel Al-Faqee said, our Shaikh Abul Fadl Al-Hamdaani said, ‘’The innovators (in) Islam and the fabricators of Hadeeth are worse than the Mulhiddoon [i.e. the heretics 1], for the heretics aim to corrupt Islam from the outside, whilst these (people) want to corrupt it from within. They (i.e. the innovators and the fabricators of hadeeth) are similar to the people of a country who try to corrupt its state of affairs and the heretics are similar to those who lay a siege from the outside; so the ones from within (i.e. the innovators and fabricators of hadeeth) open the fortress. Therefore, they are more harmful to Islam than those who do not (attribute) themselves to it outwardly.
Complete Il-haad is to turn away from Islaam completely and that is Major Il-haad, which exits a person from the fold of Islaam, such as the Il-haad of the communists, the idol worshippers and those similar to them.
And Minor Il-haad does not exit a person from the Religion of Islaam, such as turning away from some actions. Allaah (The Most High) said: [وَمَن يُرِدْ فِيهِ بِإِلْحَادٍ بِظُلْمٍ نُذِقْهُ مِنْ عَذَابٍ أَلِيمٍ] ”And whoever inclines to evil actions therein or to do wrong, him We shall cause to taste a painful torment.” [22:25][for further details, see links http://www.ajurry.com/vb/showthread.php?t=13326 http://www.ibnothaimeen.com/all/noor/article_1802.shtml
 [Quoted by Shaikh Rabee (may Allaah preserve him) in his Book titled: Al-Mahajjah Al-Baydaa Fee Himaayati As-Sunnati Al-Gharraa’i Min Zallaati Alhlil Akh’taa Wa Zayghi Ahlil Ahwaa’ page: 47]
Abu Mu’aawiyah (Abdullah Al-Gambi)