Nothing is impossible with God.
When Abraham was 99 years old, GOD again appeared to him. Now, GOD had already told Abraham that he would have a son, but that was before Ishmael was born. This time, GOD revealed that the promised son was not Ishmael but would come from Sarah instead.
And this time, GOD spoke directly to Sarah, as well as to Abraham:
1 Then God appeared to him at the oak of Mamre, as he was sitting in the tent door during the noon hour. 2 So he lifted his eyes and looked, and behold, three men stood before him; and when he saw them, he ran from the tent door to meet them, and bowed himself to the ground, 3 and said, “O Lord, if I have now found grace in Your sight, do not pass by Your servant. 4 Let water be brought, and let them wash Your feet, while You cool Yourselves under the tree. 5 And I will bring bread for You to eat. After that You may pass by, inasmuch as You have come to Your servant.” They said, “Do as you have said.” 6 So Abraham hurried into the tent to Sarah and said, “Quickly, make ready three measures of fine meal; knead it and make cakes.” 7 Then Abraham ran to the herd, took a young calf, tender and good, gave it to his servant, and he hastened to prepare it. 8 He also took butter and milk and the calf he prepared, and set it before them; and he stood by them under the tree as they ate.
9 Then He said to him, “Where is Sarah your wife?” He replied, “Here, in the tent.” 10 Again He said, “I will certainly return to you according to the time of life, and behold, Sarah your wife shall have a son.” (Sarah was listening in the tent door behind him.) 11 Now Abraham and Sarah were old, well advanced in age; and Sarah had passed the age of childbearing.
12 Therefore Sarah laughed within herself, saying, “I have not yet had a child until now, and my lord is old also?” 13 Then the Lord said to Abraham, “Why did Sarah laugh within herself, saying, ‘Shall I surely bear a child, since I am old?’ 14 Is anything impossible with God? At the appointed time I will return to you, according to the time of life, and Sarah shall have a son.”
15 But Sarah denied she had laughed, for she was afraid, saying, “I did not laugh”; but He said, “No, but you did laugh.”
(Genesis 18:1-15 OSB)
Sarah laughed because, physically, women her age (and men Abraham's age) didn't bear children. To put it in today's terms, could you image a 90 year old woman at the grocery store carrying her infant? That would be shocking! Miraculous!
When Sarah laughed to herself, GOD called her on it and reminded her that nothing is impossible for GOD.
We have previously established that:
Since these things are true, it is completely logical that the same GOD could suspend or make an exception in His designed order so that He could bring about a specific outcome. Such events are known as miracles.
We have also previously established the link between faith and outcomes. Had Abraham not believed GOD's promises, GOD would not have performed these miracles and brought about these blessings for Abraham. He would have chosen someone else (who did have faith). But, at the same time, knowing the future, GOD foreknew that Abraham did and would have such faith and that is why He called Abraham to follow Him in the first place.
The same GOD is just as alive, just as present, and just as willing to work in the lives of those who have faith today. Nothing is impossible with GOD.