1 Corinthians 7:15-16

But if the unbelieving partner leaves, let him leave. In such cases the [remaining] brother or sister is not [spiritually or morally] bound. But God has called us to peace. For how do you know, wife, whether you will save your husband [by leading him to Christ]? Or how do you know, husband, whether you will save your wife [by leading her to Christ]?