Answer:
The central idea of the passage is that the people of Northumbria were terrified by the heathen men who invaded their land and destroyed the church of God in Lindisfarne. The passage describes dreadful forewarnings that occurred before the invasion, including immense sheets of lightning, whirlwinds, and fiery dragons flying through the sky. These events served as ominous signs of the impending attack.
The passage does mention the presence of fiery dragons in the sky, but it does not suggest that they directly attacked Northumbria. Instead, they are described as part of the terrifying phenomena that preceded the invasion. Similarly, while whirlwinds are mentioned, they are not presented as an attack on Northumbria but rather as one of the forewarnings that frightened the people.
The primary focus of the passage is on the invasion itself and its impact on Northumbria. The phrase "harrowing inroads" indicates a violent and destructive attack by heathen men. The mention of the destruction of the church of God in Lindisfarne further emphasizes the severity of the invasion and its impact on religious institutions.