Canon 72 No marriage between Orthodox and heretics

Let it not be lawful for an Orthodox man to be joined to a heretical woman, nor indeed for an Orthodox woman to be yoked with a heretical man; but if anything of the kind should appear to have been done by anyone whatever, let the marriage be held void, and the lawless cohabitation be dissolved; for one must not mingle what cannot be mingled, nor join the wolf with the sheep, and the lot of sinners with the portion of Christ. And if anyone transgresses what we have decreed, let him be excommunicated. But if some, while still in unbelief and not yet numbered in the flock of the Orthodox, were joined to one another in lawful marriage, and then the one, having chosen the good, ran to the light of the truth, while the other was held fast by the bond of error, not choosing to gaze upon the divine rays (and the unbelieving wife is well pleased to live with the believing husband, or conversely the unbelieving husband with the believing wife), let them not be separated, according to the divine Apostle: for the unbelieving husband is sanctified in the wife, and the unbelieving wife is sanctified in the husband.