Final answer:
Ephesus is likely the city in the textbook statement referring to high levels of Satanic activity and demonic oppression during the Apostle Paul's ministry, notable for its significance in the spread of early Christianity.
Step-by-step explanation:
According to the textbook, of all the cities where Paul ministered, perhaps Ephesus had more evidence of Satanic activity and demonic oppression than any other place. Ephesus was a city where Christianity spread amidst great religious diversity and where believers encountered significant spiritual challenges. The Apostle Paul's engagement with the cities of the ancient Mediterranean world, as mentioned in his Epistles, clearly shows Ephesus as being significant due to having the Tomb of St. John the Apostle, indicating its importance in the spread of early Christianity and the resistance it faced from established pagan beliefs and practices.