Voltaire famously stated, "whoever can make you believe absurdities can make you commit atrocities." It is helpful to see the following full quote in which this line appears, to understand the meaning of this oft-cited maxim:

"Formerly there were those who said: You believe things that are incomprehensible, inconsistent, impossible because we have commanded you to believe them; go then and do what is unjust because we command it. Such people show admirable reasoning. Truly, whoever can make you believe absurdities can make you commit atrocities. If the God?given understanding of your mind does not resist a demand to believe what is impossible, then you will not resist a demand to do wrong to that God-given sense of justice in your heart. As soon as one faculty of your soul has been dominated, other faculties will follow as well. And from this derives all those crimes of religion which have overrun the world."  

In other words, being compelled to believe untruths, and indeed obvious untruths which you know in your heart are untrue, and then living your life as if these untruths are true, can have a morally corrosive effect and prime you to conform with terrible crimes. 

George Orwell illustrates this phenomenon well in his novel '1984', in which he explains that the dictatorial and brutal government at the center of this story rules the population and gains its buy-in to the awful system in which it lives by forcing the people to believe in and even repeat absurd, nonsensical slogans such as "war is peace" and "freedom is slavery."

Today, one of the real-life versions of these types of absurdities that large swaths of the population are being forced into believing is that our biological sex does not matter; that whether we have XX or XY chromosomes (or the incredibly rare variation between the two, which is often referred to as being 'intersex') is irrelevant to whether we are actually women or men. The most extreme version of this cult-like belief system is that people are merely 'assigned' one of the two sexes at birth by doctors and midwives – of course based on obviously visible sex characteristics – but that this designation is ultimately random and subject to change at any time by any individual, including young children whose brains have not fully developed, who may decide they are the opposite gender, or something in between the male-female binary, or even something else entirely.