The Roman Catholic Church began keeping an Index of Prohibited Books from 1558 as a direct response to the threat posed by the Protestant Reformation, which was being fuelled by print. The widespread availability of printed books allowed new, heretical ideas, particularly those of reformers like Martin Luther, to circulate widely and challenge the Church's authority and doctrines. By creating the Index, the Church aimed to regain control over information, suppress dissent, and protect the faith of its followers by explicitly forbidding them from reading books that were deemed heretical or damaging to Catholic beliefs.