There is only one way leading upwards for all who see, lightened with heavenly light. But many and dark and contrary are the ways of those who see not. This way leads to the Kingdom of heaven, uniting man to God: but those ways bring down to death, separating man from God. Therefore it is necessary for you and for all who care for their own salvation to make your course unswerving, firm, and sure by means of faith.
–Saint Irenaeus of Lyons (late Second Century)