When we read the very beginning pages of the book, we say that Hazrat Masih Maud (as) explains that this book is written to defend the Prophet Muhammad (sa) who was the one sent for the revival of mankind. When we look at Islam and the teachings, we should thank Allah for granting us such a perfect religion. He (as) then speaks about tauheed as well.
Now when we read from page 70, we see that Hazrat Ahmad (as) is defending the teaching of polygamy while the other people have even allowed adultery. He (as) presents the example of niyog. The bible also does not stop such evil. Therefore, these teachings are not complete. But in Islam, it was once allowed that if someone was on travel, and left for many years, he would take the woman with him but if she did not want to go, he would do another nikah in that country. But in Christianity, even when there is an extreme case, there is no permission for a second nikah. For this reason, many of the Christian nations fell into sin. For this reason, the government also faced this difficulty. He (as) then explains that the government is ahead in many areas, but in this area they failed. He (as) gives the example of the whites of the country, that when they needed a nikah, because of the religious ban on them, they were unable to do the nikah. He (as) says that the government is facing this problem and that polygamy would have saved them. The government was unable to change this law. At the end, they decided that the whites should have illegitimate relations with women. He (as) then quotes Akhbar-e-Am of 9 November 1895.
These are not the words of Hazrat Ahmad (as) rather the words of the newspaper to show the horrible condition of the Christians and others who have denied Islam and how they are now suffering in the worst ways. He (as) quoted this to condemn this immoral teaching and was showing them that the Islamic teaching would have saved them. He (as) said that you are in such problems because you rejected Islam.
Some anti-Ahmadis quote the book The Great Reformer, also known as Mujadid-e-Azam in the Urdu language. However, this is not a book of the Ahmadi Muslims rather the Lahoris. The Lahoris also made the same mistake as the anti-Ahmadis but were corrected by the Ahmadi Muslims in Tarikh-e-Ahmadiyya volume 1. In fact, the Lahoris also corrected themselves on their blog later on.