There is a famous question on the first pasouq of parashat Toledot:
"This is the account of Abraham's son Yisshaq. Abraham became the father of Yisshaq." (Genesis 25,19)
In Hebrew the verse tells us "Avaraham holid et Yisshaq" - literally, Abraham "gave birth" to Yisshaq. Our rabbis ask: if the verse first tells us that Abraham's son was Yisshaq, then the ending of the verse is obvious! We know that Abraham became the father of Yisshaq. What purpose does the ending of the verse serve?
Rashi answers that after the Torah tells us that Abraham's son was Yisshaq, the Torah must tell us that Abraham "gave birth" (holid) to him. Why? Rashi explains that the "Lessaneh Hador," the foolish people (those who try to undermine the faith), will raise doubt and say that Sarah became pregnant from Avimelech. They contended that Sarah was with Abraham for many years, never conceived, and suddenly after the episode with Avimelech (who took Sarah for a wife- briefly) she conceived a child. Therefore, they reasoned and promulgated, Avimelech must have fathered Yisshaq.
What did Hashem do? Yisshaq physically resembled Abraham to such a degree that everyone testified, "Abraham gave birth to Yisshaq." Their relationship was obvious to all, giving the foolish no possible way to contend that Sarah conceived from Avimelech.
One question remains about the true intention of these foolish people. A great rabbi once asked: had the foolish people succeeded in convincing the world that Sarah conceived from Avimelech, they would still have to admit that a great miracle occurred to Sarah. Be the father Avraham or Avimelech, Sarah was still a ninety year old woman who gave birth, proving the existence and intervention of Hashem.
So what was their true intention?
These individuals were not trying to deny that the miracle actually occurred, but rather they were trying to change who the miracle happened for; had they succeeded, we would be forced to say that a miracle occurred for Avimelech Harasha. This would allow the foolish to claim that Hashem does perform miracle, but not just for the righteous. This philosophy has dangerous ramifications. Knowing that a miracle can occur for anyone, we are no longer interested in learning from Avraham's righteous ways and incorporating his behavior into our lives. Just as our rabbis in the past guided and protected us from false philosophies, we too should be careful to guard ourselves and our children from such faulty ideologies from seeping into our homes.