Which One Is More Severely Punished: The Sinner or The Innovator?

Shaykh Saalih bin Fawzaan bin 'Abdullaah al-Fawzaan حفظهُ اللهُ تعالىٰ was asked: 

"Which one is more severely punished: The sinner or the Innovator?" 

He responded with saying: The innovator; because the innovation is more severe than the sin (1) and the innovation is more beloved to the Shaytaan؛  because the sinner repents(and the sinner doesn't because he thinks what he is doing is correct). 

As for the Innovator few repent, because he thinks he's on the haqq, unlike the sinner. He knows he's a sinner and that he's a perpetrator of a sin. As for the innovator, he views himself obedient and that he's upon obedience.  Henceforth it becomes a bid'ah (that he perpetrate). 

I seek refuge in Allaah from the evil of sin. Due to this the Salaf use to warn from sitting with the innovator (2) because they have an effect on those that sit with them, and their danger severe. No doubt that bid'ah is eviler than the sin. And the danger of the innovator is more severe upon the people than the danger of sinner (due to what was mentioned previously) (3). Due to this, the Salaf said:

"Frugality in the sunnah is better than striving in innovation." (4)

Source: 

  الأجوبة المفيدة عن أسئلة المناهج الجديدة : لمعالي الشَّيخ الدُّكتور: صالح بن فوزان بن عبد الله الفوزان
 
Translator:
Abu Abdul-Haadee Khaleel Davis 
                 
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(1 ) إن الله حجب التوبة عن صاحب كل بدعة

"Indeed Allaah places a covering of
 the tawbah from the  companion of every bid'ah."

رواه إسحاق في مسنده، والطبراني في الأوسط ، والبيهقي في الشعب و الهيثمي في مجمع الزوائد , ورجاله رجال الصحيح غير هارون بن موسى الفروي, وهو: ثقة.
وقد حسنه المنذري، وصححه الألباني

Reported by Ishaaq in his Musnad, and at-Tabbaraani in al-Awsat , and al-Bayhaqi in Ash-Shu'ba  and Al-Haythumi in Majmu' az-Zuwaaid and the men in it are saheeh other than Haaroon ibn Musa al-Farwee, and he is trustworthy. Al-Muntharee said it is good and shaykh Al-Albaanee authenticated it.  

(2 ) قـال الحسن البصري - رحمه الله -: « لا تجالس صاحب بدعة ؛ فإنه يمرض قلبك » . « الاعتصام » : ( 1 / 172 ) ، «  البدع والنهي عنها »: ( ص : 54 ) .
Al-Hasan al-Basree said may Allaah have Mercy on him. "Do not sit with the innovator, indeed he will make your heart sick." Al-'Itisaam 1/172 The Innovation and Prohibition from It: page 54.

 (3 )قال سفيان الثَّوريِّ - رحمه الله -: « البدعة أحبُّ إلىٰ إبليس مِنَ المعصية ؛ فإنَّ المعصية يُتاب منها ، والبدعة لا يُتاب منها » . «  مسند ابن الجعد » : ( 1885 ) ، «  مجموع الفتـاوىٰ »  : ( 11 / 472 ) .

Sufyaan ath-Thawree may Allaah have Mercy on him said: " The innovation is more beloved to Iblis than sin; indeed the sin is repented from, but the innovation isn't. 
Musnad ibn Ja'd 1885 , Majmu al-Fataawa 11/472

(4) من قول ابن مسعود - رَضِيَ اللهُ عَنْهُ - ،  اللالكـائي : ( 114 ) ، «  الإبانة  » :   (161) ، « السُّنَّة » لابن نصر : (30) ،  الصَّحيحة » : ( 5 / 14 ) . 

From the Statement of ibn Mas'ud may Allaah be pleased with him.  Al-Lalakaa'ee 114,  al- Ibaanah 161 as-Sunnah of Ibn Nasr page 30, as-Saheehah 5/14