I do not think it would be a stretch to infer from the life-script of God’s calling of Abraham to say that the desire to produce a family was a high-priority in the information-package divinely created within the “seed” that describes the person and character of Abraham.
Abraham has everything…wealth, possessions, servants, and a beautiful wife he loves…but he does not have a family upon arrival in Canaan.
At the very center of the God-composed life-script for Abraham is a promise of descendants as numerous as the dust of the earth, pinpointing at the outset of his calling a divinely created, in-built desire-of-the-heart for Abraham that is accurately utilized by God in fashioning Abraham to become over time, through a series of divinely crafted events the “father of faith.”
Yet this same created, innate desire for a normal family-life also produces the context for the problem with Sarah, Hagar, and Ishmael.
This sets-up the supreme challenge of faith for Abraham on Mount Moriah (modern day Jerusalem) that may be the most difficult test that any human being has ever been asked of God to face, other than Jesus Christ as the Passover Lamb of God two thousand years later at Calvary.
In other words, God not only crafted the life-script adventure of faith for Abraham, but God as Creator placed within Abraham the unique information-content of being the right “seed” to take this adventure of faith on God’s terms all the way to a successful conclusion, to produce good fruit (Heb. 11:17-19; Rom. 4:3).
What makes the biblical narrative stories of faith so extraordinary as to validate their divine origin starting with Abraham, is that Abraham’s own ability to produce children of promise through Sarahneeded to fall into the ground to die like a seed in order to rise up as a supernaturally endowed and beneficial life-story.
This then rises far above the worldly conventionality of self-produced outcomes through autonomous individualism (Gen. 17:15-19).
It would appear from the biblical narrative stories of faith that the big-picture, fundamental objective is worldly unconventional to the core.
The big-picture objective gleaned from the biblical narrative stories of faith examples is not to validate our worth and value according to self-reliant self-achievement (Mk. 8:36) using our created talents and abilities apart from God, but instead to validate an entirely different objective.
That entirely different objective is to create the unique contexts for biblical faith to actualize into personal relationships between people and God, at the height of our created purpose and destiny.
Can Abraham produce children on his own within worldly conventional normalcy and thinking, without God’s divine intervention, outside of the promises of God?
The answer is yes.
After the death of Sarah, Abraham took another wife, Keturah, who gave birth to Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah.
We should not forget that Abraham produced Ishmael his first son through Hagar (Gen. 16:15).
But we do know from scripture (Gen. 17:19) that Abraham cannot produce Isaac the son of promise, other than through Sarah.
The three men that visited Abraham and Sarah in the plains of Mamre recorded in Genesis chapter 18, the leader being called Lord by Abraham (I believe this was Jesus the Son of God) confirms for us that in this critical opening scenario introducing the biblical narrative stories of faith, this worldly unconventional and innovative component of God validates His divine participation in the affairs of mankind.
This is for the highest imaginable reasons.
The life-story of Abraham does not validate the fact that Abraham is capable of producing a large and happy family-life on his own according to conventional thinking, but instead that God can create the new reality of biblical faith as defined in Hebrews 11:1.
The life-script for Abraham has a gap in time between the initial calling of Abraham with God’s promise of descendants as numerous as the dust of the earth, and the fulfillment of this promise coming years later, that forms the context for this biblical faith to actualize into real human life experience.