Complex sentence: However, the Nazi "kirchenkampf" campaign against the Churches altered his conviction, and he was expelled from the Nazi Party, and by the outbreak of World War Two, Stellbrink had become a firm opponent of the Nazi movement.
Split into simpler sentences: However, the Nazi "kirchenkampf" campaign against the Churches altered his conviction, and he was expelled from the Nazi party. By the outbreak of World War II, Stellbrink had become a firm opponent of the Nazi movement.