In his 1846 encyclical, Qui Pluribus, Blessed Pius IX charged the Church’s shepherds with protecting the purity of the Catholic Faith: “So, in accordance with your pastoral care, work assiduously to protect and preserve this faith. Never cease to instruct all men in it, to encourage the wavering, to convince dissenters, to strengthen the weak in faith by never tolerating and letting pass anything which could in the slightest degree defile the purity of this faith.”