In the KJV Paul writes: "For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy." A Christian married to an unbeliever need not fear that the marriage defiles them - the marriage stands holy before God and the children are counted holy, not unclean.
Not in the sense of being saved by the marriage itself. Following John Chrysostom's comment on the verse, the lesson explains that although husband and wife are one flesh, the believer's cleanness overcomes the unbeliever's uncleanness - the believing spouse is not made unclean by the union, yet the unbelieving partner still needs to come to faith.
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