How does Genesis 21:5 connect to God's covenant with Abraham in Genesis 17? The Texts at a Glance • Genesis 17 records God’s covenant confirmation with Abram, changing his name to Abraham and promising a son through Sarah. • Genesis 21:5 reports the exact fulfillment: “Abraham was a hundred years old when his son Isaac was born to him.” The Promise Stated: Genesis 17 • 17:1-2 — “I am God Almighty; walk before Me and be blameless. I will establish My covenant between Me and you…” • 17:4-5 — “You will be the father of a multitude of nations.” • 17:7 — “I will establish My covenant as an everlasting covenant between Me and you and your descendants after you.” • 17:17, 19 — Sarah herself will bear the promised son, and his name will be Isaac. • 17:21 — “My covenant I will establish with Isaac, whom Sarah will bear to you at this time next year.” The Promise Fulfilled: Genesis 21:5 “Abraham was a hundred years old when his son Isaac was born to him.” Key details: • Abraham’s age precisely matches the timetable God set in 17:21. • Isaac’s birth validates the covenant sign given the previous year (17:23-27). • The seemingly impossible circumstances spotlight God’s power and faithfulness (cf. Romans 4:19-21). Connections Between Chapter 17 and 21 • Same Parties — God and Abraham remain central, underscoring covenant continuity. • Specific Son — Isaac is named in advance (17:19) and named again at birth (21:3-5), tying the chapters together. • Timetable Kept — The phrase “at this time next year” (17:21) is answered by the time-stamp “a hundred years old” (21:5). • Covenant Line — Isaac’s arrival locks in the “everlasting covenant” line that will pass to Jacob and the tribes (26:3-5). • Sign and Substance — Circumcision (17:10-14) marked Abraham’s household; the birth of Isaac supplies the covenant substance those marks anticipated. Implications for Our Faith • God’s word is exact; He fulfills promises down to ages and names. • Delays are not denials; twenty-five years after Genesis 12, the covenant child arrives. • The covenant depends on divine power, not human ability—Abraham (100) and Sarah (90) were beyond natural hope. • Trusting God’s timing brings joy; Sarah laughs in disbelief at promise (17:17) and later in delight at fulfillment (21:6). Scripture Echoes • Numbers 23:19 — “Does He speak and not act? Does He promise and not fulfill?” • Isaiah 46:10-11 — “My purpose will stand, and I will do all that I please.” • Hebrews 11:11-12 — Sarah conceived because she “considered Him faithful who had promised.” • Galatians 4:28 — “Now you, brothers, like Isaac, are children of promise.” Genesis 21:5, therefore, is the tangible seal that God’s covenant words in Genesis 17 were not merely lofty ideals but living, time-stamped realities—anchoring our confidence that every promise of God will likewise come to pass. |
    |