Fides et Ratio. This encyclical, promulgated by Pope John Paul II on September 14, 1998, deals primarily with the relationship between faith and reason. Faith needs reason, for without reason, it leads to superstition. Reason without faith leads to nihilism and relativism. John Paul II states that modern philosophy has taken wrong turns and fallen into area. It is the magisterium's responsibility to respond when controversial philosophical opinions threaten right understanding of what has been revealed and when false theories sow the seeds of error, confusing the faith of the People of God. The key to the document is the appeal that faith and philosophy recover that profound unity which allows them to stand in harmony without compromising their mutual autonomy.