1 Corinthians 7:14 - Ellicott's Commentary On The Whole Bible

The unbelieving husband is sanctified by the wife. — Any scruple which a Christian might have felt as to whether matrimonial union with an unbeliever would be defiling is here removed, and the purity of the former teaching justified. In contrast to that other union in which the connection is defiling (1 Corinthians 6:16), the purity of the believing partner in this union, being a lawful one, as it were, entirely overweighs the impurity of the unbeliever, it being not a moral, but a kind of ceremonial impurity. The children of such marriages were considered to be Christian children; and the fruit being holy, so must we regard as holy the tree from which it springs. It must be remembered that the “sanctification” and “holiness” here spoken of is not that inward sanctification which springs from the action of the Holy Spirit in the individual heart, but that consecration which arises from being in the body of Christ, which is the Christian Church (Romans 9:16.)