Is it permissible to cooperate with an Ash'ari man in creed in calling to Allah (Mighty and Majestic) if leaving that off leads to harms?

The questioner : from Fikri: He says: Is it permissible to cooperate with an Ash'ari man in creed in the field of calling to Allah on the grounds that this disagreement in creed does not lead to harms, but rather that not cooperating with him may lead to the division of the efforts of the Muslims?

The Shaykh : If cooperating with such a man does not lead him, through that cooperation, to be lax in his creed, then that is permissible without a doubt. In fact, I believe that it is among the religious interests of the strong believer in faith to cooperate with other Muslims who have deviated from the Salafi creed due to old or recent causes. It is more fitting for this Salafi believer to cooperate with these people, because he will find the appropriate opportunity to convey the Salafi call to them. And what happens, and we know that by experience, is that the position of those opponents toward this righteous Salafi believer will be one of two things: either they will respond to his call, inclining to accept the Salafi school and deviating from their Khalafi school, and this has happened often; or they will reject him and his school, and they will refuse to deal with him, in which case the matter returns to him and not to them.