The record in Genesis 25 is not a record of blessing; rather, it is a record of remarriage. Abraham married Keturah after Sarah died. Is remarriage a sign of the maturity in life? Certainly not!
Abraham's life may be divided into three sections: the section with Ishmael, the section with Isaac, and the section with the six sons. Ishmael was produced by Abraham's flesh, and Isaac was produced by God's grace. What about the six sons? They were produced by even more flesh. After the birth of Ishmael, Abraham's flesh was dealt with, and grace came in to replace it. But after the birth and growth of Isaac, Abraham's flesh became active again. In the first section, the section with Ishmael, Abraham's flesh was onefold, but in the third section, the section with the six sons, his flesh was sixfold, having been intensified six times. While the younger flesh produced one Ishmael, the older flesh produced six sons.
The Bible is honest, telling us that Abraham married Keturah and begat six sons by her. But Abraham knew God's will. Verse 5 says, "Abraham gave all that he had unto Isaac." Isaac was the unique heir, the heir chosen, designated, and established by God. None of the other sons were reckoned as heirs (v. 6), for they were all sons of the concubine and, like Ishmael, were rejected by God. Abraham had two concubines. The first gave birth to Ishmael, and the second gave birth to six sons. But God did not want any of them. Both before and after the birth of Isaac, Abraham did something which God did not want. How can we say that such a life is mature?
The intention of Genesis 25 is to show that Abraham did not have the maturity in life. He died without this, for as we have seen, he died without blessing anyone. Although Abraham was good, he was not mature in the divine life. It is right that we appreciate him, but we must realize that he had a great lack. He was called, had faith, and lived in fellowship with God, but, to use a New Testament term, he did not have sufficient transformation.
What is transformation? Once again I would like to use the example of petrified wood. As water flows through the wood, the element of wood is carried away and the elements of minerals are added in its place. As the mineral elements are wrought into the wood, the wood is transformed into stone. This is petrification. We are wood, and the flow of living water must carry away our natural element and bring into our being all the divine, heavenly, holy, and spiritual elements. In this way we are transformed.
If you read chapters twenty-three through twenty-five again, you will see that Abraham was not a fully transformed person. He was a man who lived in fellowship with God and who acted according to His leading, but he was not transformed in full. Rather, he remarried and exercised the flesh which had been dealt with by God to bring forth six more "Ishmaels." Although we must be like Abraham, we need to see that in himself he was not a complete pattern.