There are many reasons why Vikings may have raided monasteries. One reason is that Vikings were looking for valuables such as gold and silver. Monasteries often had large amounts of these precious metals, making them a tempting target for Viking raiders. Another reason is that monasteries were often isolated, making them easy targets for surprise attacks. Additionally, the monks who lived in monasteries were not trained in combat, making them easy prey for Viking warriors. Finally, raiding monasteries was a way for Vikings to show their power and dominance over other groups. By plundering these religious institutions, Vikings sent a clear message that they could strike at anyone, anywhere.