Their salvation still requires belief and repentance just as the rest of us. This sanctification he is speaking of is of a setting apart. There are varying levels of sanctification. The unbeliever and the household are being blessed tangibly because of the blessing of God toward the believer and the children are raised in a better and more wholesome environment. It still would be better however that they all believe.
These are general rules for marriage but, the principals involved are far reaching. Principal one: you are not your own, you are the others'. Principal two: don't hold back yourselves from one another except by mutual consent for spiritual matters. Principal three: stay engaged/invested in the marriage even if your spouse is a unbeliever if they are consenting.
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