I have Tahmid-ul-Iman translated...mashAllah, what a masterpiece Sayyiduna alaHazrat radhiy Allahu `anhu wrote!
alaHazrat says: According to the scholars, Ahle Qibla are those who have firm faith on all essentials of the faith. (Tamheed-e-Iman Bi Ayat-e-Quran P.32)