> Genesis 20:11–12
>
> And Abraham said, “Because I thought, surely the fear of God is not in this place; and they will kill me on account of my wife. But indeed she is truly my sister. She is the daughter of my father, but not the daughter of my mother; and she became my wife.

> Deuteronomy 27:22
>
> ‘Cursed is the one who lies with his sister, the daughter of his father or the daughter of his mother.’ And all the people shall say, ‘Amen!’ [Also see Leviticus 18:6–9.]

These two passages, to some, present quite a contradiction. Genesis tells us that Abraham, a man blessed by God, married his half-sister, while Moses in Deuteronomy tells the Israelites that anyone who lies with his sister shall be cursed. So, is this a contradiction in the Bible? Not at all!

We need to keep in mind that the Law of Moses was not given until around 1440 BC, long after the time of Abraham. From the historic Christian theological perspective, early in human history, close intermarriage was necessary to fulfill God's command to be fruitful and multiply and populate the earth.

As humanity expanded, God instituted laws against close intermarriage (as detailed in Leviticus 18) to widen the bonds of charity and human fellowship across different families, as taught by early Church Fathers like St. Augustine and St. John Chrysostom. Thus, what was initially permitted by necessity was later forbidden by the Law in order to structure a holy society for Israel. Furthermore, God's revelation of His moral law was progressive, culminating in the complete and perfect law of Christ.

So, once again, we see that there are no contradictions in the Scriptures when we take the time to study them in their proper historical and theological context.