Simplify the following text for a Grade 8 native English-speaking person.
Original: Under the city 's protection , they were able to form their own reformed church under John Knox and William Whittingham and eventually carried Calvin 's ideas on doctrine and polity back to England and Scotland .
Simplified: With the city 's protection , they could make their own reformed church under John Knox and William Whittingham . They later carried many of Calvin 's ideas back to England and Scotland .