By faith Sarah herself also received strength to conceive seed, and she bore a child when she was past the age, because she judged Him faithful who had promised (Heb 11:11)

    While addressing the Galatians in his letter to them, Paul spoke about Abraham, saying, “His son by the slave woman was born in the ordinary way; but his son by the free woman was born as the result of a promise.” (Gal 4:23 NIV). Remember, the “slave woman” here, refers to Hagar, while the “free woman” refers to Sarah. Concerning Sarah, our main Scriptural text says, “…she bore a child when she was past the age, …” (Heb 11:11). Recall our earlier description of the process of human reproduction. It implies then that Sarah conceived, carried the pregnancy to term and then bore Isaac when she was past the age! What that shows us is that: the way in is the way forward. Meaning that, what it took her to conceive, was what it took her to carry the pregnancy to term and bear her son. We know what it took was God’s strength, which she had RECEIVED. This shows that the same Divine strength it will take you  to conceive the vision of God for your life is still what it will take to see it to fulfilment. It is important to know this because sometimes we behave like the Galatians, whom Paul asked, “Are you so foolish? Having begun in the Spirit, are you now being made perfect by the flesh?” (Gal 3:3). The flesh (‘human effort’ in the  NIV) can never succeed in completing whatever the Spirit initiates. Paul rightly refers to any attempt to do that as foolishness. If nothing short of God’s power could have enabled Sarah to conceive, it would be foolish then to imagine that she could have sustained the pregnancy and brought forth Isaac by anything less. Only God can complete what He has begun (Philip 1:6).
    The reason for the foregoing is that the Bible refers to Sarah as the free woman whose son was born as the result of a PROMISE. This is in contrast with Hagar’s son, who was born in the ORDINARY way (Gal 4:23). While the birth of Isaac was the result of a prophetic word, the birth of Ishmael was not. God does not work until He speaks. His prophetic word initiates His work and His work can only be accomplished by His power. In fact, the Greek word translated into English as ‘strength’, in relation to Sarah in our main text above, is ‘dunamis’ and it means miraculous power. We can see that what Sarah herself received from God was miraculous power. However, one of the reasons why she was able to receive that power (strength) was because God had made her a promise earlier on. Therefore, she had a prophetic word. Since Isaac was the promised heir, God’s power had to be the means of the fulfilment of His promise.  Ishmael, on the other hand, was born in the ordinary way because God did not speak a word concerning his birth. His conception and subsequent birth were, in fact, an unsuccessful attempt to adjust and modify God’s promise. See what God says concerning Himself: “you who call yourselves citizens of the holy city and rely on the God of Israel–the LORD Almighty is his name: I foretold the former things long ago, my mouth announced them and I made them known; then suddenly I acted, and they came to pass.” (Isa 48:2-3 NIV). God refers to Himself as ‘Almighty’ in the Scriptural text above, and as such, whatever He foretells and announces, His acting in power brings to pass.
         In conclusion, however, Sarah was able to receive strength from God to conceive and ultimately bear Isaac, not only because God Himself had given her a promise to that effect, but, “…because she judged Him faithful who had promised.”  Yes she had her moments of weakness in which she faltered but, she did not give up on the One who had promised. She judged Him faithful in spite of the perplexing contradictions she was faced with. This implies that Sarah did not evaluate God’s willingness or His ability to fulfil His promise on the basis of her circumstances. Though her situation was beyond human remedy, she judged Him faithful who had promised, because her  assessment of both God’s willingness and ability to make good His promise was based on His character and nature. If we let our experiences, feelings or circumstances determine how we assess God, we are bound to misjudge Him.  It is how we judge God with regard to His promises to us that will ultimately determine whether we can receive from Him. Shalom.