6 You know very well, Venerable Brethren, that even when surrounded by tribulation the Church still enjoys some consolation from God. "Christ also loved the Church, and delivered himself up for her, that he might sanctify her...in order that he might present to himself the Church in all her glory, not having spot or wrinkle or any such thing, but that she might be holy and without blemish." When vice runs wild, when persecution hangs heavy, when error is so cunning that it threatens her destruction by snatching many children from her bosom (and plunges them into the whirlpool of sin and impiety) - then, more than ever, the Church is strengthened from above. Whether the wicked will it or not, God makes even error aid in the triumph of Truth whose guardian and defender is the Church. He puts corruption in the service of sanctity, whose mother and nurse is the Church. Out of persecution He brings a more wondrous "freedom from our enemies." For these reasons, when worldly men think they see the Church buffeted and almost capsized in the raging storm, then she really comes forth fairer, stronger, purer, and brighter with the lustre of distinguished virtues.
Source: Editae Saepe (Vatican.va)