Intro
In 1911, an Ahmadi, Muhammad Zahir Al-Din wrote a book wherein he discussed the prophethood of MGA and its implications of Kufr upon the Muslims of the world.  Mahmud Ahmad quotes this book in his 1924 book, “The truth about the split” and Muhammad Ali has quoted him quite a bit also in his books vs. Mahmud Ahmad.

The full book
Nabee Allah Kaa Zahoor Mukamal

Other essays on this topic
https://ahmadiyyafactcheckblog.com/2017/01/04/nabi-ullah-ka-zahoor-aka-appearance-of-the-prophet-of-allah-1911-by-muhammad-zahir-al-din/