Short Answer 
Concentration camps and ghettos were integral to the Nazi strategy during WWII, where Jews and other minorities were isolated and subjected to desperate conditions leading to mass executions. While some found temporary safety in churches, these were not primary detention sites, highlighting the systematic nature of the persecution.
Step 1: Understanding Concentration Camps
After the outbreak of WWII, many Jewish people were forcibly taken to concentration camps, which served as detention facilities established by the Nazis. These camps were designed to hold Jews and other minorities deemed undesirable. Over time, many camps were converted into death camps where mass executions tragically took place.
Step 2: The Role of Ghettos
Jewish populations were also placed in ghettos, which were segregated neighborhoods intended to isolate them from the rest of society. These ghettos were often overcrowded and lacked basic necessities, leading to inhumane living conditions. This isolation was part of a broader strategy to control and eventually deport Jewish people to concentration camps.
Step 3: Temporary Refuge in Churches
While some Jewish individuals sought temporary refuge in churches and other hiding places, these were not the primary locations for mass detainment. Although sympathetic individuals helped provide safety, such sheltered spots were rarely secure in the long term. Overall, small German villages and other countries did not serve as main sites for the detainment of Jewish people during this period.