Without self-knowledge you have no root in yourselves personally; you may endure for a time, but under affliction or persecution your faith will not last. This is why many in this age (and in every age) become infidels, heretics, schismatics, disloyal despisers of the Church. They cast off the form of truth, because it never has been to them more than a form. They endure not, because they never have tasted that the Lord is gracious; and they never have had experience of His power and love, because they have never known their own weakness and need.
John Henry Newman, Parochial and Plain Sermons [Complete]
christianity, god, god-s-grace, heretics, infidels, self-knowledge, the-church