Mixed marriages violate the nature of the intimate relationship that marriage creates. Marriage creates a family and God’s people are to serve Him in their families. Families are the primary unit of spiritual nurture in the covenant of God because they are the instrument by which and the setting in which children are not only born but raised. Families have a great deal to do, in the economy of God’s grace, with the transmission of the faith from one generation to another. They must because of the nature of the relationship between parents and children: the intimacy, the constancy, the dependence, the trust, the example, the instruction that happens in a family and, especially, in a godly family. To take an unbeliever to wife, to bring into that family circle, in the key role of wife and mother, a woman who does not love God or know his salvation, who does not reverence his Word and law, is to violate the very purpose of a family and render it incapable of being and doing what it has been created for... He made the family, the godly family the instrument of his grace in the children’s lives. But a spiritually mixed marriage injects poison into the children’s milk.