God's ideal was always that we should avoid divorce; the preservation of a marriage depends on both wills, however, and one partner can sometimes end a marriage unilaterally against the other's will (see comment on 1:19). Roman law permitted either party to divorce the other; Jewish law permitted the husband to divorce the wife, regardless of the wife's wishes (Keener 1991a:51).

Matthew mentions an exception to the general rule about divorce: except for marital unfaithfulness, or literally (and more ambiguously) except for porneia, sexual immorality. The NIV probably rightly interprets the sense for this context, which provides a specific exception for those already married. When Matthew speaks of this exception, his readers very probably would have understood this as a legal charge (as in Quint. 7.4.11; Suet. Julius 6, 74), hence as referring to unfaithfulness; thus, for example, the wife's adultery exempted the husband from returning her funds to her (Safrai 1974-1976b:790). Jewish and Roman law both required divorce for these grounds (Safrai 1974-1976b:762; see comment on 1:19). Matthew's audience would thus probably interpret these words in line with the typical meaning of "infidelity," namely, sexual unfaithfulness to the marriage, as grounds for divorce. Mark and Luke probably could assume such an exception without explicitly stating it (Carson 1984:418). As France puts it (1985:124): To repudiate a wife after she had committed adultery was therefore simply the recognition that the marriage had already been terminated by the creation of a new union. . . . The Matthaean exceptive clause is . . . making explicit what any Jewish reader would have taken for granted when Jesus made the apparently unqualified pronouncements of Mark 10:9-12.

I believe that most other views of porneia in this text fail to treat Matthew's specific cultural setting adequately (taking into account the "charge") beyond their own proposal. Most of these views also give porneia ("immorality," "infidelity") a more restricted meaning than it normally bears unless explicitly qualified, which it is not here (as noted by many commentators, such as Hagner 1993:124). They also miss how such a term (used in its unqualified, general sense) would function in a usual legal context (see above). Most views other than the infidelity view imply that Matthew permits divorce only when the original marriage is not valid, but divorce was unnecessary in the case of invalid marriages; further, such marriages were not common enough to warrant Matthew's mention.

"Except for infidelity" may modify Jesus' statement about divorce rather than remarriage (Heth and Wenham 1984:117; G. Wenham 1984 and 1986; compare against this position Murray 1953:39-43), but if it does, it does so precisely because in Jesus' graphic statement it is the validity of the divorce that is in question. No one permitted remarriage if a divorce was invalid, but a valid divorce by definition included the right to remarry, as is attested by ancient divorce contracts (see, for example, m. Gittin 9:3; CPJ 2:10-12, 144; Carmon 1973:90-91, 200-201) and the very meaning of the term (besides sources in Keener 1991a, see, for example, Jos. Ant. 4.253; Blomberg 1992:111). Jesus' point is at any rate not to break up second and third marriages (even for guilty parties)-as if the hyperbolic element in his graphic statement might be missed-but to underline in no uncertain terms the sanctity of marriage and our solemn responsibility to preserve it when this is at all possible. Thus most conservative Christian writers acknowledge some cases where divorce and remarriage are permitted (for example, Dobson 1986:68; Adams 1980:86-87).