Christians. Even today they are still being persecuted in many countries, I don't know why the media doesn't report on it, but it's still happening.
Jews were targeted by Nazis as weakening Germany. Many were imprisoned and executed. Another ethnic group involved in Nazi genocide were the Romani (gypsies).
Most of the persecution is religious-based, but some people fear the unknown.
Probably the group most opposed to socialism were the Fascists of the 1930s who actively persecuted socialists.
Muslim
Chriatian.
Catholics
Sunni Muslims.
The Jews suffered the most.
Unitarians
The Puritans
In polling, the largest single group is "no religious affiliation." Protestantism is the most practiced religious sect, followed by Catholicism. Sikhism is the largest non-Christian religious group.
The most common religious group in the colonies was the Presbyterian group, which was the religion of some famous founding fathers such as George Washington etc...