Since cities breed spiritual seeking, when Christians abandon cities they lose many seekers as well.
Here is just one of 10 or so ways that cities “produce seekers”. Cities attract large numbers of immigrants, many of which come from countries in which it would be very difficult for missionaries and ministries to operate. In North American cities they are, humanly speaking, far
more reachable than they would have been in their home country’s rural areas. And moving to into a new country makes immigrants more open to change, including religious change, than they would have been in their home country. That’s just one example.
The city is obviously not the only fruitful setting for evangelism, but there is none better