I have reproduced an extract from the book Truth About The Split by Mirza Mahmood Ahmad, son of the holy prophet of Ahmadis and also prophesied by his father and “Prophet” Mirza Ghulam Ahmad.
Before d-tox..ed starts claiming that Ahmadiyya is not defined by a single book it is worthy of pointing out that all Ahmadi Khalifas have re-affirmed the beliefs of Mirza Mahmood Ahmad. Secondly his son claims in the extract below that his father Mirza Ghulam Ahmad also held these same views and produces proof of this , or at least so he claims.
"Regarding the main subject of my article, I wrote that as we believed the Promised Messiahas to be one of the Prophets of God, we could not possibly regard his deniers as Muslims. It is true we did not consider them to be kafir billah, (deniers of God), but how could we doubt that, they were kafir-bil-ma’mur (deniers of a God’s Messenger)? Those who say that they regarded Mirza Sahib as a righteous person and so did not deserve to be called kuffar, ought to consider whether a righteous person ever spoke an untruth. If Mirza Sahibas, was indeed a righteous person, what possible objection could there be to their subscribing to his claim.
After this, the article proceeded to quote passages from the writings of the Promised Messiahas to show that he regarded his deniers as kuffar. Some of the passages, quoted in the article, are reproduced here in brief: To the apostate Abdul Hakim of Patiala, he wrote: “At any rate, when the great God has revealed to me that every body whom my Call has reached and who has failed to
accept my claim, is not a Muslim, and is liable to account before God, how can I at the instance of one individual, whose heart is steeped in a thousand darknesses, ignore the command of God. It is easier to cut off such a one from my Community. Accordingly from this date I hereby exclude you from the Community of my followers.” **Following this, I proceeded to explain the purport of the above passage in the following words. "The above words apply not merely to those who take an active part in denouncing the Promised Messiahas; but every person who fails to accept him is not a Muslim. **Further on, I explained, in the words of the Promised Messiahas himself, the meaning he attached to the expression “reaching of Call.” …
After this, I went on to prove from the writings of the Promised Messiahas that those who did not explicitly style the Promised Messiahas as a kafir but nor did they accept his claim, were to be classed with those who styled him as a kafir; so also were those who only waited for fuller information and put off entering into his Bai‘at. Then in my own words. I summarised the purport of the quotations as follows:“Thus, according to these quotations, not only are those deemed to be kuffar, who openly style the Promised Messiahas as kafir, and those who although
they do not style him thus, decline still to accept his claim, but even those who, in their hearts, believe the Promised Messiahas to be true, and do not even deny him with their tongues, but hesitate to enter into his Bai‘at, have here been adjudged to be kuffar." After this, some more quotations were given in support of the main contention, and the weakness implicit in the overture for friendship was exposed, and the Promised Messiah’s as fatwa (pronouncement) which forbade Ahmadis to pray behind non-Ahmadi Imams was quoted. And lastly, it was argued from a verse of the Holy Quran that such people as had failed to recognise the Promised Messiahas as a Rasul even if they called him a righteous person with their tongues, were yet veritable kuffar.”
This book can be read here at the official Ahmadi website:
http://www.alislam.org/library/books/Truth-about-the-Split.pdf
There are also numerous other passages in this book which I will high light when time permits.