Ante-Nicene Fathers, Vol VII:
Lactantius: Chap. LXVI.—Of faith in religion, and of fortitude

Chap. LXVI.—Of Faith in Religion, and of Fortitude.

Faith also is a great part of justice; and this ought especially to be preserved by us, who bear the name of faith, especially in religion, because God is before and to be preferred to man. And if it is a glorious thing to undergo death in behalf of friends, of parents, and of children, that is, in behalf of man, and if he who has done this obtains lasting memory and praise, how much more so in behalf of God, who is able to bestow eternal life in return for temporal death? Therefore, when a necessity of this kind happens, that we are compelled to turn aside from God, and to pass over to the rites of the heathens, no fear, no terror should turn us aside from guarding the faith delivered to us. Let God be before our eyes, in our heart, by whose inward help we may overcome the pain of our flesh, and the torments applied to our body. Then let us think of nothing else but the rewards of an immortal life. And thus, even though our limbs should be torn in pieces, or burnt, we shall easily endure all things which the madness of tyrannical cruelty shall contrive against us. Lastly, let us strive to undergo death itself, not unwillingly or timidly, but willingly and undauntedly, as those who know what glory we are about to have in the presence of God, having triumphed over the world and coming to the things promised us; with what good things and how great blessedness we shall be compensated for these brief evils of punishments, and the injuries of this life. But if the opportunity of this glory shall be wanting, faith will have its reward even in peace.  

Therefore let it be observed in all the duties of life, let it be observed in marriage. For it is not sufficient if you abstain from another’s bed, or from the brothel. Let him who has a wife seek nothing further, but, content with her alone, let him guard the mysteries of the marriage-bed chaste and undefiled. For he is equally an adulterer in the sight of God and impure, who, having thrown off the yoke, wantons in strange pleasure either with a free woman or a slave. But as a woman is bound by the bonds of chastity not to desire any other man, so let the husband be bound by the same law, since God has joined together the husband and the wife in the union of one body. On this account He has commanded that the wife shall not be put away unless convicted of adultery, and that the bond of the conjugal compact shall never be dissolved, unless unfaithfulness have broken it. 1590 This also is added for the completion of chastity, that p. 251 there should be an absence not only of the offence, but even of the thought. For it is evident that the mind is polluted by the desire, though unaccomplished; and so that a just man ought neither to do, nor to wish to do, that which is unjust. Therefore the conscience must be cleansed; for God, who cannot be deceived, inspects it. The breast must be cleared from every stain, that it may be a temple of God, which is enlightened not by the gleam of gold or ivory, but by the brightness of faith and purity.  

Footnotes

[The law of divorce in Christian States. Sanderson, v. iv. p. 135.]