Many world religions have religious doctrine that forbids or frowns upon the marriage of outsiders (exogamy). Sometimes this is defined as people with wrong beliefs and is designed to protect believers from being exposed to outside ideas. Scriptures warn that intermarriage brings god's wrath and makes people impure. Anthropologists suspect that in some situations, the argument that "the bloodline must be kept pure" is actually an excuse to justify practices that are really just power-games (i.e., the prevention of land becoming inherited by non-family-members). Often, such rules stem from racist and xenophobic instincts. Nearly always, dogmas against exogamy result in prejudice and de-humanization of outsiders, leading in some cases to faith-based sectarianism, religious intolerance and extremism.
Rules against marrying outsiders can lead to widespread incest1, especially in small communities, and this leaves distinct biological markers upon our genetic ancestry, hence we have often discovered periods of inbreeding amongst religious groups through the study of family genetics. Luckily, in the modern world, most people ignore their religions' prohibitions against exogamy, and scriptural verses on the matter are rarely repeated by religious leaders. The world has moved on morally, and negative judgements based on others' faith or skin colour are no longer popular barriers to marriage.
The Hebrew Scriptures / Christian Old Testament has many stories warning against marrying foreigners. Deuteronomy 7:3-4 and Ezekiel 20:32-34 says believers are not to marry nor live among non-believers because foreign women will "turn away" men from worshipping God - the punishment is God's anger and losing God's favour. Malachi 2:11-12 says the same thing, but also adds that the descendants of such unions will also be punished (so much for free will). Ezra has long been a source of racism and pointless sectarianism. It says when his people marry outsiders, it offends God and "corrupts" the community (Ezra 9:2). Learning of intermarriage causes the prophet Ezra to tear his clothes, pluck out his beard hair and sit down astonished (9:3). This prejudice and intolerance is found again in Ezra 10:2-3, 10-12 where 113 men are forced to abandon foreign wives else face God's wrath. Continuing this, Neh 13:23-27 has a holy man chastising and punishing mixed-culture families and forces believers to promise they will no longer marry or let their sons marry foreign women. In Numbers 25: 6-15 another holy man is rewarded by God for murdering a newly wed husband and foreign wife (Zimri and Cozbi) for the offence of marrying an outsider, because God had sent plagues as a result of such impurities.
“In Orthodox Judaism, anyone born of a Jewish mother is Jewish. Non-Jews can convert to Judaism on marriage, but one of the biggest problems facing Judaism today is the loss of numbers caused by marriage between Jewish men and non-Jewish women. [...] In Britain, the number of Jews has fallen from 500,00 thirty years ago to fewer than 300,000 today, mostly as a result of marrying out. Increasingly, Jewish communities outside Israel are seeking to find ways of amending the rules [...]. Many Jewish leaders see this as the most difficult challenge facing Judaism.”
Sociologists have often commented on the reluctance, and often refusal, of Jewish rabbis to conduct marriages between Jews and non-Jews: "Mayer conducted a 1997 survey of American rabbis on interfaith marriages, in which 36 percent of the rabbis said that they would officiate at an interfaith wedding, but the numbers ranged widely, from zero among the Orthodox and Conservatives rabbis to 62 percent of the Reconstructionist rabbis (Mayer 1997)"3.
Deuteronomy 7:3-4: Believers are not to marry the non-believers of Canaan because these foreign women will "turn away" their sons from worshipping the God of the Bible. The punishment is God's anger.
Ezekiel 20:32-34 warns that families of believers cannot live out in the world with non-believers, and if they do, they will incur the anger of God.
Malachi 2:11-12 warns believers that people "desecrate the sanctuary" if they marry "women who worship a foreign god". Such people lose the favour of God, and any sacrifices they make for god are no longer accepted happily - and - crying about it won't help. This also applies to the descendants of those involved (so much for moral justice!). The solution is not to marry women of the wrong religion in the first place.
Ezra 9-10: Ezra has long been a source of racism and pointless sectarianism. It says when his people marry outsiders, it offends God and "corrupts" the community (Ezra 9:2). Learning of intermarriage causes the prophet Ezra to tear his clothes, pluck out his beard hair and sit down astonished (9:3). This prejudice and intolerance is found again in Ezra 10:2-3, 10-12 where 113 men are forced to abandon foreign wives else face God's wrath.
“I rebuked them and called curses down on them. I beat some of the men and pulled out their hair. I made them take an oath in God's name and said: "You are not to give your daughters in marriage to [foreign women's] sons, nor are you to take [foreign women's] daughters in marriage for your sons or for yourselves."”
Neh 13:23-27 contains a little story about a holy man, Nehemiah, who goes around chastising and punishing mixed-culture families. His main issue that many believers had married wives of Ashdod, of Ammon and of Moab who all worshipped other gods. He makes believers promise that they will no longer marry or let their sons marry these foreign women. It also states that the legendary King Solomon fell from grace due to his repeated relations with foreign wives.
Numbers 25: 6-15: contains another story of a priestly holy man who murders the newly wed husband (Zimri) and his foreign wife (a Midianitish woman called Cozbi) for the offence of marrying an outsider. He runs into their tent and "thrusts them through" with a spear, killing them. The aside in this story is that God has been punishing the Hebrews with plague for such impurities as it was making God jealous (verse 11). The priest therefore "saved" them all by stopping this marriage at its very beginning and he is rewarded by God for his actions, and for good measure, his children are rewarded too (verse 13).
The contributors to "The Woman's Bible" by Elizabeth Cady Stanton (1898)4 make this point on this story: "The Jewish law forbade a man going outside of his tribe for a wife. It was deemed idolatry. But why kill the woman? She had not violated the laws of her tribe and was no doubt ignorant of Jewish law"5. The horrible morals portrayed in this story (murderous xenophobia and intolerance, for the sake of doctrine) are some of the worst features of religion.
St Paul in 1 Corinthians 7:39 urges believers to marry "in the Lord", meaning, within the community of believers. 2 Corinthians 6:14-17 warns believers not to mix in with unbelievers as they have nothing in common and "what fellowship can light have with darkness?" and that believers should separate themselves from others. Many other minor verses go along the same lines: 1 Corinthians 5:9-12 says you can't even marry, or mingle with, those who are Christians but who behave wrongly and 15:33 says "bad company ruins good morals".
But despite the biblical versus warning of the wrath of god for intermarriage, St Paul is calmer in 1 Corinthians 7:12-14 which says that if you do somehow become married to a non-believer, then, you don't have to divorce them because the believer makes the other one (and the children) holy. However this verse is somewhat the odd one out compared to the others.
The Qur'an talks in a similar way to other Abrahamic religions, for example Sura 60:10 says "Do not maintain your marriages with unbelieving women: demand the dowries you gave them" or just "hold not the disbelieving women as wives" depending on the translation. This means you cannot marry a non-Muslim and if your wife converts away from Islam, then, you have to divorce her and get back the money you paid for her (the dowry). The IHEU reports that in many Islamic states, it is illegal for women to marry non-Muslims. This happens in Brunei, Djibouti and Sudan, plus a large range of Islamic states in the Middle East and surrounding area7.
Judaism, Christianity and Islam are the three most well known monotheistic religions. All three were preceded by the first great monotheistic religion, Zoroastrianism, which also contains rules against marrying outsiders. There are still communities of Zoroastrians around today - in India they are called Parsis, and, for historical reasons, there is a small community of Parsis in Hong Kong. Caroline Plüss's study of this community revealed some side-effects of such rules being strictly adhered to:
“Parsis in Hong Kong, despite considerable economic integration and some political integration during Hong Kong's colonial rule, never seriously challenged Zoroastrian rules forbidding exogamy. Such deliberate differentiation was not lessened by the fact that the Parsi community in Hong Kong never counted more than 100 members, and needed to rely on the much larger community in Mumbai to find spouses (Plüss 2005:209), or by the fact that the Zoroastrians' strong inclination not to accept conversions has accounted for significantly declining numbers of Zoroastrians worldwide.”
She doesn't mention incest (perhaps such a close-knit community is loathe to admit it to outsiders), but it is easy to see that while such rules might suit an expanding religion, as soon the situation changes, they become a detriment to the moral standing, genetic health and long-term growth of a religion, let alone being based, from the very start, on a form of xenophobic prejudice.