http://apologeticspress.org/AllegedDiscrepancies.aspx?article=2281&b=Genesis
Inconsistencies About Incest?
by Eric Lyons, M.Min.
On more than one list of “Bible discrepancies” is the allegation that Bible writers erred in their teachings about incest. In Leviticus 18:6-30, 20:11-12, and Deuteronomy 27:20-23, one learns that sexual relations between close family members is sinful and punishable by death: “None of you shall approach anyone who is near of kin to him, to uncover his nakedness” (Leviticus 18:6). Other passages, however, indicate that God tolerated incest among His people, and even blessed those involved in such relationships. Abraham married Sarah, his half-sister (Genesis 20:12; cf. Genesis 17:15-16; 22:17), while Abraham’s son, Isaac, married Rebekah, his second cousin (Genesis 22:20-23; 24:4,15), and Jacob, Abraham’s grandson, married his first cousins, Rachel and Leah (Genesis 24:29; 29:15-30). Even Moses’ father, Amram, “took for himself Jachebed, his father’s sister, as wife” (Exodus 6:20, emp. added; cf. Leviticus 20:19). Critics claim that such passages are contradictory. Were Bible writers really inconsistent when they addressed the subject of incest?
First, one must recognize that simply because Scripture mentions godly men such as Abraham or one of his righteous descendants doing something God forbade elsewhere, does not mean the Bible writers contradicted themselves. Christ was the only perfect man ever to live (2 Corinthians 5:21). Though Noah, Abraham, Moses, etc. were counted faithful to God (Hebrews 11:7-29), they occasionally disobeyed His will (e.g., Numbers 20:1-12). God never blessed their disobedience, only their faithfulness. Consider the harlot Rahab. Whereas God did not condone her harlotry, she was “justified by works when she received the messengers and sent them out another way” (James 2:25). “By faith the harlot Rahab did not perish with those who did not believe, when she had received the spies with peace” (Hebrews 11:32). Simply because God graciously saved Rahab from the destruction of Jericho, does not mean that God condoned her past sexual sins. Similarly, just because the Bible writers mention a particular event (e.g., Amram marrying his aunt) without condemning it, does not necessarily mean the Bible writers condoned it.
Second, for one to identify a legitimate contradiction, he must be considering the same time frame. To condemn Thomas Jefferson for not paying Federal income tax would be inappropriate because there was no Federal income tax in the United States during his lifetime. Likewise, to accuse certain righteous men of breaking God’s law prior to the establishment of that law is equally erroneous. The first indication of God forbidding incestuous marriages is not until after the Israelites departed Egypt (when Moses was already 80 years old—Exodus 7:7). Prior to Mosaic Law, men could lawfully marry close family members. Indeed, God blessed Abraham (Genesis 12:1-3) while he was married to Sarah, his half-sister. What’s more, implied in the creation of Adam, the first man (1 Corinthians 15:45), and Eve, “the mother of all living” (Genesis 3:20), is that their immediate offspring married each other and had children. Furthermore, following the great Flood, the entire Earth was repopulated by Noah, his three sons, and their wives (Genesis 9:1). Thus, in the beginning God allowed incest.
There was no need for strict laws on marriage partners in the early Patriarchal Age (apart from the divine “one man, one woman, for life” institution), and for at least one good reason: during this time, man was in a relatively pure state, at least physically, having left not long before the perfect condition in which he was created and the Garden that had sustained his life....[N]o harmful genetic traits had emerged at this point that could have been expressed in the children of closely related partners. However, after many generations, and especially after the Noahic Flood (Genesis 6-9), solar and cosmic radiation, chemical and viral mutagens, and DNA replication errors, led to the multiplication of genetic disorders. God protected His people by instituting strict laws against incestuous marriages in the eighteenth chapter of Leviticus (Thompson and Major, 1987, 7[2]:7).
Laws regarding incest were given only during the Mosaic dispensation. Those living prior to this period or since this age ended (Colossians 2:14) have not been bound by its laws on incest anymore than we are bound by other Mosaic mandates (e.g., refraining from eating pork—Leviticus 11:7). That said, since “more genetic disorders have arisen in the world population since the time of Moses,...it is even more important to avoid marrying a close relative. Christianity thus far has insured that such rules have been carried forward into modern laws in the western world” (Thompson and Major, 7[2]:7). Though it may not be sinful for you to marry your first cousin, you may need to think twice before saying, “I do.”
REFERENCE
Thompson, Bert and Trevor Major (1987), “Where Did Cain Get His Wife?” Reason and Revelation, 7[2]:5-7, February.