Afzal Upal covered this topic in his recent book on Ahmadiyya, see page 28.

Some common Ahmadi arguments
1—–if Mirza Ghulam Ahmad is not form Allah how did his message reach Africa, Ghana. Qadian, his birth place is even unknown in India as we speak. How did his travel this far and you are there with all your knowledge and insults.

2—- this is what your grandfathers and ancestors did and still Mirza Ghulam Ahmad message is reaching all the corners of the earth.

3—Just like infidels of Mecca did a social and economical boycott of of OUR Holy Prophet Peace and Blessings of Allah be upon him.