Q:Given the following passage  "During the Republic, any person who wished to hold public office had to conform to the Reformed Church and take an oath to this effect. The extent to which different religions or denominations were persecuted depended much on the time period and regional or city leaders. In the beginning, this was especially focused on Roman Catholics, being the religion of the enemy. In 17th-century Leiden, for instance, people opening their homes to services could be fined 200 guilders (a year's wage for a skilled tradesman) and banned from the city. Throughout this, however, personal freedom of religion existed and was one factor – along with economic reasons – in causing large immigration of religious refugees from other parts of Europe.",  answer the following question. Note that the answer is present within the text.  Question: what group is mentioned first?
A:
the Reformed Church