Steipler in Karyane DeIgrata VOL 1 clearly says the belief in the medina as athalta digeoulah ,while a big mistake [!] , is not kfirah.
Al pi ha’emet , It is a descent into a more dark form of galut than previous galuyot .
To experience a galut between our own errant and hateful brothers.
But this mistaken belief of athaltah d/g is definitely not kfira.
Please check inside the sefer.
It is not kfirah .
Black on white.
It’s there.
Maskana :
Athaltah d/g is not heresy.