❖ Atheists and Their Demands for Rational Proof
Atheists frequently demand rational arguments for every Islamic belief or law. Yet, when confronted with a simple rational question — “If there are supposed benefits to sibling marriage, what are the purely rational arguments against it?” — they immediately shift to moral justifications.On one hand, they demand rational proofs for laws rooted in Qur’anic moral teachings, but on the other, they invoke morality when rationality doesn’t suffice for their own worldview. This double standard reveals that they operate with two distinct kits: one rational, the other moral. When logic fails, they flip the switch to morality — a strategy they refuse to accept from believers.
Thus, they are obligated to present rational reasons against sibling marriage with the same intellectual rigor they apply when denying the existence of God.
❖ Examining the Atheists’ Arguments
① The Risk of Birth Defects ArgumentA common argument is that incestuous relationships (e.g., between siblings or parent and child) pose a higher risk of producing children with disabilities, making such acts rationally wrong.
However, this argument assumes without proof that having children without disabilities is a moral good, which itself needs justification. Moreover, if contraceptive measures are taken, then by their logic, there remains no rational objection to such relationships.
Therefore, rationality alone cannot definitively declare such acts morally wrong.
② The Social Disapproval Argument
Another claim is that such relations provoke parental and societal outrage. The answer is simple: this emotional reaction is based on pre-existing societal norms where incest is viewed as immoral.
If one imagines a society where such behavior is normal, the emotional and social reaction would vanish — just like how, in the West, a father may not be troubled by his daughter having a boyfriend, while in our society this is a source of grief.
It’s hypocrisy to provoke rebellion against God’s authority while simultaneously conforming to social pressures. Why do those who don’t fear God fear society?
③ The Adam and Hawwa Argument
Some argue: “You believe sibling marriage was allowed for Adam and Hawwa’s children, but now you call it forbidden.” This response is a deflection, not a rational argument against the act itself. It does not answer why they refrain from such marriages today based solely on rational grounds.
❖ The Religious Perspective
According to religious belief, good and evil are defined by God.If Allah declared sibling marriage permissible during the time of Adam and later forbade it, it was right then and wrong now.
We respond to Allah’s commands with “We hear and we obey”. Our sense of disgust toward such acts stems from our acceptance of God’s moral framework.
But the real question remains:
What rational argument do those who reject divine morality have for abstaining from sibling marriage?
"Produce your proof if you are truthful." (Qur’anic principle)
❖ The Limits of Reason
To declare something rationally lawful or unlawful, an ethical framework must first be assumed. This is a limitation of reason often ignored.The atheist tactic is to smuggle their unproven ethical assumptions into the definition of rationality and use this to mislead believers by claiming, “We use reason, you rely on faith.”
❖ The Need for Revealed Morality
The truth is, when morality is detached from revelation, man is left in a state where reason fails to provide clear direction, and all paths appear equally valid.A Prophet is the divine rope that helps mankind identify the correct direction through God’s guidance.
