Shaykh Zayd al-Madkhalee, rahimahullah, said:

وأهل بدع فسقة من الفساق ،ليسوا كفاراً -كأهل الحزبيات، والمنظمات المخالفة لمنهج أهل السنة والجماعة فى باب الجهاد ، وفى باب النصيحة ، وفى باب الأمر بالمعروف ، وفى باب الولاء -ونحو ذلك- ؛ فهؤلاء نعم يُدعى لهم بالهداية.
فإذا ماتوا وهم على الإسلام: لا حرج من أن يُترحّم عليهم ، فيقول: رحمه الله .
لكن ؛ لا يعلن ويشهر تحسّره عليه ؛ لأن صاحب البدعة من أعداء أهل السنة ، فلا يُظهر أهلُ السنة الأسفَ عليه ؛ لأن موته خير لأهل الأرض من بقائه ، فبحكم الإسلام: له أن يترحّم عليه بينه وبين نفسه ، فلا يُعلن ذلك ؛ لأن خطر أهـل البدع واضح ومعلوم على أهل السنة ومحاربتهم لها .

“… The people of innovations are people of fisq [i.e wrongdoing], they are not disbelievers. This is the case regarding the people of hizbiyyah and the associates of organizations which oppose the methodology of Ahlus Sunnah Wal Jama’ah in relation to the issue of Jihaad and in the issue of naseehah and in the issue of commanding the good and the issue of giving allegiance and the likes of it. So yes, du’a is to be made for the likes of these people that they become guided, and if they die while they are upon Islam, then there is no problem in asking Allah to show mercy upon them. So, he would say, ‘rahimahullah’ [i.e. may Allah have mercy upon him]. However, he shouldn’t annoucce it [i.e. to the public] nor display sorrow for him since he is an innovator from the enemies of the people of the Sunnah. Thus, he shouldn’t display any sorrow for him, the reason being his passing away is better for the people on the Earth than him remaining. So based upon the right of Islam, then he should make du’a to himself that Allah have mercy upon him, [but] he should not announce it [i.e. to the public] since the danger of the people of innovations is something clear and well known against Ahlus-Sunnah and how they wage war against them [i.e. Ahlus-Sunnah] “