Inform the shelterers of the innovators about this praiseworthy characteristic of the Imaams of the Sunnah
بِسۡمِ ٱللهِ ٱلرَّحۡمَـٰنِ ٱلرَّحِيمِ
Shaikh Saaleh Aala Shaikh (may Allaah preserve him) said:
Giving importance to the Sunnah and refuting the innovators is (something) manifest in the (religious) affairs of the Imaams of Islaam. Indeed, their lives were (spent) in refuting the innovators and they did not busy themselves with refuting the ‘Kuffaar Asliyyeen’ (i.e. those who do not ascribe themselves to Islaam)-the disbelieving Jews and Christians.
And if you look at the statements of Imaam Ahmad, Sufyaan, Hammaad Bin Zayd, Hammaad Bin Salamah, Nu-aym Ibn Hammaad, Al-Awzaa’ee, Ishaaq, Ali Ibn Al-Madeenee and their likes amongst the Imaams of the Sunnah, you will find that their speech and striving was in refuting the innovators and in declaring their principles faulty, even though they (i.e. the innovators) were still upon that basis that kept them within the fold of Islaam.
They (i.e. the Imaams of the Sunnah) did not busy themselves with refuting the Jews, the Christians and all the other religions of disbelief, and that is because the evil of innovators is not manifested to the people of Islaam and the people of Islaam are not safe from it. As for the Kaafir Asliy [i.e. the one who does not ascribe himself to Islaam], then the evil and harm (of his religion) is manifest and clear to every Muslim.
[Slightly paraphrased & abridged. For further details, see Sharh Lum-atil Ittiqaad: page 155]