The allegation which the non Ahmadi Muslims raise against Hazrat Mirza Ghulam Ahmad(as), is that he believed Isa(as) to be the son of Yusuf Najjar. They quote Izala Auham page 303, and nothing of this sort is stated there nor in any books of Ahmad(as). Yusuf Najjar was the stepfather and also the foster father of Jesus(as). Calling Yusuf Najjar the father of Isa(as) referring to him being the step and foster father is nothing wrong and is normal in conversations. This would only be wrong if the topic being discussed was in regards to a blood parent. Sadly the non Ahmadi Muslims do not want to give even a little bit of respect to Yusuf Najjar.
Mary(as) is herself reported to have called Yusuf Najjar the father of Jesus in the Bible. It is stated:
“Said to him, Son, Why have you treated us this way? Behold, your father and I have been anxiously looking for you” (Luke Chapter 2 Verse 48)
The anti Ahmadis are trying to raise a false allegation, that Ahmad(as) denied the virgin birth and did not believe in it. This is totally false as Ahmad(as) made it clear in many writings, that Isa(as) was born without a father. Ahmad(as) stated:
“God Almighty had informed the Jews through some of His prophets that a son from among them would be born without a human father” (Hammamatul Bushra, Page 90, Ruhani Khazain, Volume 7 Page 315)
He (as) also stated that “The first thing which He did to bring this about was the craetion of Hazrat Jesus(as) without the agency of a father through the manifestation of His Divine powers only” (Mawahibur Rahman, Page 72, Ruhani Khzain Volume 13, Pages 290-291)
Ahmad(as) also stated:
“On a perusal of the Holy Qur`ān, this is what emerges as the truth, namely, that Jesus was fatherless; and this is a matter on which no question can come to lie. Where Allāh calls this birth as resembling the birth of Adam, it is an indication that in this birth there is an element of an extraordinary process of nature, to which a reference had to be made, for an explanation, by likening it to the example of Adam.” (Badr , May 16, 1907, page 3)
Again Ahmad(as) states:
“Our faith and belief is this that Jesus was born of no father, and Allāh has the power to do all things. The rationalists, called Naturies among us, who try to establish that he was born of a human father they are making a serious blunder.The Lord God of such people is a dead Lord God. The prayers and supplications of such people are not granted who assume that Allāh cannot cause a child to be born independently of the agency of a human male in the role of a father. We consider a man who holds this view to have fallen out of the pale of Islam.” ( Al-Hakam, June 24, 1901)
Now the non Ahmadis lie in regards to the belief of Ahmad(as) but forget to mention, that people from their own ummah in reality hold such a belief which was opposite to the belief of Ahmad(as). Allama Abdul Quyyum Qayumi has stated “It is a matter of great astonishment that despite the fact that Mary was married, yet the son to whom Mary gave birth is stated to have no father” (Qayumi Allama Abul Quyyum, Haqiqat al Masih Page 237)
This belief is shared by many scholars of the Ahle Hadith and of the Ahle Qur’an. Maulvi Hafiz Inayatullah Wazirabadi also believed that Isa(as) had a father (Inayatullah Maulvi Hafiz Uyoon Zamzam fi Milad Isa Ibn Maryam Pages 172-176)
The same belief was held by Ghulam Parvez (Parvez, Ghulam Ahmad, Shulah Mastur Pages 132-133)