But there is hardly anything more serious than to be joined in marriage to a stranger (i.e., to an unbeliever), where the instigations both of lustful appetite and of disharmony and the shameful crimes of sacrilege are welded together. For if marriage itself needs to be sanctified by the priestly veil and blessing, how is it possible to speak of a marriage where there is no agreement in faith?
God's Scripture gives proof in numerous passages that man must undergo many disturbances in this life; and also that many consolations are at hand. With these, a spirit of sufficient vigor and awareness of the right should overcome present discomforts and look to those things that promise everlasting joy.
When a man gives God his secret things, that is, his mind and thoughts, not occupying himself elsewhere, nor wandering away, but putting constraint upon himself, then the Lord deems him worthy of mysteries, in greater sanctity and purity, and gives him heavenly food and spiritual drink
Do not neglect the practice of the virtues; if you do, your spiritual knowledge will decrease, and when famine occurs you will go down into Egypt (Genesis 41:57, 46:6).
And the old man also said, 'God saith unto thee thus -- if thou lovest Me, O monk, do that which I ask, and do not that which I do not desire. For monks should lead lives wherein they act not in iniquity, and a man should not look upon evil things with his eyes, no hear with his ears things which are alien to the fear of God, nor utter calumnies with his mouth, nor plunder with his hands; but he should give especially to the poor, and he should not be unduly exalted in his mind, and he should not think evil thoughts, neither should he fill his belly. Let him do then all these things with discretion, for by them is a monk known.' The old man also said, 'These things form the life of a monk: good works, and obedience, and training. A man should not lay blame on his neighbor, and he should not utter calumnies, and he should not complain, for it is written, 'The lovers of the Lord hate wickedness.'