for Adam's sons and Noah's grandchildren
A recurring question, asked in hundreds of different ways, relates to where Adam's sons and even Noah's grandchildren get their respective spouses. A cursory read of Scriptures shows they certainly did marry and have offspring. What makes this an issue is the perceived violation of our present morality. If Adam's sons married sisters, or Noah's grandchildren intermarried, isn't this incest and forbidden by Scriptures?
Notice that in the first definition the closely related marriage is forbidden by custom or is illegal. Customs are the common practice of a society or a group of people. Laws are the encoding of such practices by a competent governing authority. For this reason customs and laws can vary throughout the world, some being completely in opposition to another.3 For the purposes of this article, as a biblical examination, the narrow focus must be God's customs and laws, not the divergent standards of the world. The real question is, "Was and is marriage between brothers and sisters incest by God's authority?"
With Adam and Eve, Scripture is clear that they were the first human beings God created. Their special creation was the beginning of the human race, with the remainder of mankind their descendants.
In the Bible's big picture, every person who has or will live on this planet is related. More specifically, each man and woman of the generation following Adam and Eve were their children. Somehow people often think that Adam and Eve only a few sons - namely Cain (Genesis 4:1), Abel (Genesis 4:2), and Seth (Genesis 5:3) - leaving a huge question as to where these sons subsequently got their wives. But Scriptures is very clear that Adam and Eve lived extraordinarily long lives and continued to have numerous additional sons and daughters.
These sons and daughters intermarried, easily creating a population explosion within a generation! Cain married his sister (or perhaps niece); Seth married another sister (or perhaps niece), and so on. Their intermarriage was a necessity as no unrelated humans existed on the planet. Immediately the thought of brothers and sister marrying causes great consternation to some: isn't that a sin of incest?
So is this incest? By our current legal and cultural standards, and recent historical standards, the answer is yes! Consider another dictionary definition of incest.
While it's incest to us, it was only incest to the ancients if forbidden "by (their) law or taboo." The issue here is what was morally and legally correct at that time. God is the absolute lawmaker (and was actually the only Lawmaker in the beginning). The Bible shows us that there was no prohibition to marriage of close relatives until quite some time after creation. And this does make sense. Every rule God has established is based upon one of two things: (1) His holiness, or (2) His desire to protect us from harm. Regarding the first, anything that opposes, or falls short of, the absolute standard of God's holiness is sin (Romans 7:7, 1 John 3:4). These things are unchangeable forever because God, Himself, cannot change (Malachi 3:6, Hebrews 13:8). Beyond those, God out of His love for us established at various times laws and regulations to protect us. God can, and has, legitimately changed these at various times. For example, consider many of the rules first implemented in the Mosaic Law 1. Incest laws fit into this category as well.
Certainly, we know why incest is harmful present day; the intermarriage of close blood relatives substantially increases the risk of serious genetic defects.4 In fact, in humankind as a whole, genetic problems are increasing. As a species, man's DNA is breaking down over successive generations. This makes sense in regards to Creation and the Fall. The effects of sin that started at the fall have affected all aspects of creation (Romans 8:19-22). Things are growing worse (Hebrews 1:10-12).
In contrast, Adam and Eve's DNA would have been perfect when they were created. Each generation after the fall began to see increased mutations and defects, compounding with each subsequent generation. Early on, intermarriage of brothers and sisters would've had little or no consequence and, for this reason, God didn't restrict marriage among close relatives. God's initial command to be fruitful and multiply (Genesis 1:27-28) had only two primary restrictions; (1) A man and woman were to be married, and (2) a spouse of someone else was off limits.
To the time of Abraham and Sarah marriage of brothers and sisters appears to be common and acceptable and, again, there was no prohibition from God.
The ancient records of other civilizations in the region, such as Egypt, show that sibling marriage was not uncommon among them as well, especially in regards to Pharaohs.
In the giving of the Law of Moses, for the nation of Israel, God instituted a number of rules specifically to set His people apart from the other nations and to protect them. For the first time, for this specific people, incest became taboo or illegal.
Such a prohibition was surely necessary by this time. The effects of intermarriage was likely becoming increasingly visible, due to the aforementioned genetic deterioration. Not only were the people many generations removed from Adam, their much reduced life-spans following the flood also testify to an accelerated genetic breakdown. All these generations later, it's even more necessary that we practice such a prohibitions, to protect people from what is now a clearly harmful practice.
Again, note it was only from the time of Moses onward that incest became a forbidden practice - and, even then, only among the Israelites. In earlier times, as with Cain, or Abraham, marrying a sister (or niece) was permissible. Noah's grandchildren, likewise, were freely able to marry their cousins2 or their sisters.
While some nations did have direct contact with ancient Israel, it wasn't God's Mosaic Law prohibition that likely led many other nations into adopting anti-incest laws. Like most laws, they were enacted because leaders could see that there was a problem and they then instituted a law to stop the problem. A host of children with visible problems from genetic defects, offspring from close marriages, would have led to such laws.4
Does the Bible continue the prohibition of incest as defined in the Mosaic Law? In part, this question's answer rests in your understanding of what, if any, of the Mosaic Law still applies to the church. While open to some debate, it's certain that the New Testament presupposes a standard of sexual morality. Undoubtedly this standard is the one the Israelites knew and had been taught from the Old Testament. Sex outside of marriage was sin and marriage was to be between a man and a woman. These basic fundamentals were established in the beginning. It's safe to say that God hasn't changed His primary restrictions defining sexual immorality or the practice of incest. All New Testament warnings regarding sexually immorality are based upon these standards (see 1 Corinthians 5:9-11; 6:9, Hebrews 13:4, Revelation 21:8, etc). Moreover, the apostle Paul specifically and negatively mentions child and parent incest:
Even if a Christian holds that the minutiae of the Mosaic Law no longer applies, the Law having been fulfilled in Christ, it can still be Scripturally proven that God's standard was always that a child and parent never marry. Consider these words:
This creation statement makes it clear that marriage means leaving one's parents, not marrying with them. Even the pagan world had generally continued to uphold this longstanding taboo carried tradionally since creation.
Biblical taboos on incest have been intertwined within the fabric of much of the modern world, a world historically influenced by Christianity. The New Testament is completely clear that a relationship between a parent and a child (grown or not) is incest. Since many Christians have historically taken aspects of Mosaic Law and claimed their application for the church to varying degrees, additional aspects of these Mosaic laws regarding incest have found their way into modern laws as well. In Christian nations, a strong argument exists that the governent should uphold God's standards preventing sexual immorality.
Consider nations apart from Israel, with their Mosaic Law, and those few Christian lands carrying on God's New Testament standards. We could call these pagan lands. They have no clear scriptural mandate preventing a brother and sister from marrying. It's safe to state a believer living in those lands, or interacting with people from those lands, must honor their laws (or codified customs) on this subject. Wherein that jurisdiction may allow for marriage between cousins or closer sibling relations, the church (believers) should honor these marriages. These unions are not in opposition to the aforementioned primary requirements given by God, that the marriage not be between direct descendants and only between a man and a woman. Certainly, regardless of government approval, since we have clear knowledge of possible physical problems caused by relationships between siblings or cousins, we should be cautious of ever promoting these unions.
In summary, the Bible unqestionably defines marriage between a parent and child (direct descendant) as sin. While Mosaic Law warns against other closer relationships, such as cousins and siblings, it always becomes sin for those not under the Mosaic Law if it's in violation of governmental authority. In the present era, for much of the world, marrying a sister or brother is sin. But it wasn't for Adam's kids, Abraham's kids, or Noah's grandchildren.
1. The primary function of the Mosaic Law was to show what sin is (Romans 7:7). Yet, undeniably, aspects of that law provided extra protection to the Israelites, especially in regards to contagious illnesses (Leviticus 13), contact with human waste (Deuteronomy 23:12-13), and even foods (especially under cooked pig, Deuteronomy 14:8).
2. Even in the western world, where many laws are based at least loosely upon Christian principles, there are jurisdictions were marriage to a cousin has been and is still permitted. For example, in the so-called Bible Belt, Tennessee allows marriages of first cousins (while about half of the remaining states ban such a relationship). Incest is then limited to children, grandchildren and siblings.
3. Beyond the example in end note 2, here are a few more...
(c) 2006/2009/2017 Brent MacDonald, LTM/DTI - Cottage Cove Urban Ministries