What does “but now they are holy” (1 Cor. 7: 14) mean?
The complete verse reads “For the unbelieving husband is sanctified in the wife, and the unbelieving wife is sanctified in the brother; since [otherwise] indeed your children are unclean, but now they are holy”. Now while the subject of this verse and its context is clearly that of marriage, many assume that Paul is simply arguing for the legitimacy of a marriage between a believer and an unbeliever that had taken place before the believer had been converted. However, the words used of the children here are not notha (illegitimate) and gnesia (legitimately born) but akatharta (unclean) and hagia (holy). Thus the question of the legitimacy of the marriage is not the bearing of what Paul says about the children. The true meaning is something else, and since the language employed is taken from Judaism and the OT, it is there that we must turn to find it. For Paul views the present outward position of Christians, Jew and Gentile, as rooted in Israel’s history saying later “I would not have you ignorant, brethren, for all our fathers …” (1 Cor. 10: 1, my emphasis).
God said to Israel “ye shall be to me .. a holy nation” and “a holy people art thou unto Jehovah thy God” (Ex. 19: 6; Deut. 7: 6). This holiness was national and not intrinsic although the practical reality of it was enjoined (see Lev. 11: 45). Thus the people were taught the “difference between the holy and the unholy, and between unclean and clean” (Lev. 10: 10, see also Lev. 11: 47). If a Jew profaned himself, he became unclean for a time (see Lev. 11: 36–40) but he was still a Jew and thus remained positionally holy in the sight of God.
Now the Jew had certain earthly privileges on account of birth and the apostle refers to these in Rom. 3: 1, 2: “What then [is] the superiority of the Jew? ... Much every way”. These privileges were based entirely on nationality and had nothing to do with personal faith, or its lack. Such blessings were identified with a Jew’s separate position on earth as a Jew—they belonged to earth and time, not heaven and eternity. However, in practice, a Jew could profane himself through some error and become unclean for a time. In that case, while he retained title to the privileges of Judaism as Jew, he was barred from the enjoyment of those blessings until the wrong was corrected.
Marriage between Israel and the nations was strictly forbidden (see Deut. 7: 3, 4). Hence in the recovery under Ezra and Nehemiah the confession was “We have acted unfaithfully toward our God, and have taken foreign wives of the peoples of the land ... And now let us make a covenant with our God to put away all the wives, and such as are born of them… (Ezra 10: 2, 3; see also Neh. 13: 23–25). It is against this background that 1 Cor. 7: 14 is set. In taking a foreign wife a Jew was not profane, for he was still a Jew and positionally holy, but he had profaned himself. By contrast, his children from such a union were profane and, furthermore, could not be profaned—for that which is already profane clearly cannot be made so. As profane, they were not holy, but unclean. In such a situation, the only path of recovery for the Jew was to put away his foreign wife and children.
So what is the equivalent situation in Christianity when one partner in a marriage is converted but the other remains a Jew or a heathen? Firstly, notice the comparisons and contrasts between the two positions. In a mixed marriage in Judaism, the Jew was profaned but still holy; in Christianity the unbelieving spouse was sanctified (set apart) but not personally holy. In Judaism, the children were profane and unclean; in Christianity, the children are holy. This holiness in regard of the children is not intrinsic but positional. The sanctification of the unbelieving spouse is temporal in exactly the same way as the believing Jew was unclean until matters were set right. The unbelieving spouse still needed conversion as v16 shows. The children are identified with the people of God on earth and as such are in a place of privilege that other children are not. Now though Paul lists the privileges of being a Jew in Rom. 9: 1–5, his answer to his question of Rom. 3: 1 is simply “Much every way: and first, indeed, that to them were entrusted the oracles of God” (v2, my emphasis). What then of the privileges of being part of a Christian household? Paul reminded Timothy that “from a child thou hast known the sacred letters, which are able to make thee wise unto salvation, through faith which [is] in Christ Jesus” (2 Tim. 3: 15, my emphasis). The word for child here is brephos—a new–born babe. Timothy had a godly mother and grandmother (see 2 Tim. 1: 5) but probably an unbelieving father (see Acts 16: 1). He is thus an example of what is set out in 1 Cor. 7: 14. In the house and in the assembly the children of a Christian parent have the privilege of being brought under the authority of the Holy Scriptures—so much so that Paul addresses them directly: “Children, obey your parents in [the] Lord, for this is just” (Eph. 6: 1).