“Fulan has agreed with Ahlul Bidah in such and such”
It is the kind of agreement that is restricted and specific not Absolute and general
Its place is not to be exceeded
Like the saying Fulan from Ahlul sunnah is in agreement with the Jahmiyyah or the Mutazilah or any of the sects from Ahlul-Bidah
It doesn’t mean that he is agreement with those sects in their usool (fundamental principles) and that he takes the same ruling as them.
This expression is only used to warn from his statement and that nobody deems it permissible to use his statement.
This has been explained by Shaykhul Islam in Majmoor Fatwa volume 12 page 206
“And he has become from the Jahmiyyah in some issues
Meaning he has agreed with the Jahmiyyah in it
So as to make clear the weakness of his statement and not that his ruling is like their ruling, this would not be said by the one who knows what he is saying”
Written By Ahmed An-Najjar
Translated by Jafar ibn Ruel Jeffrey