Is my statement, "If I were to find a verse that permits beating one's wife, I would not accept it," considered disbelief, given that the intention behind it is to demonstrate the impossibility of a religious text existing that allows harming and humiliating women?

The statement is an atrocity, for it contains audacity and disrespect towards the Sharia, which could lead its utterer to disbelief (Kufr). However, if it was not intended to be a mockery of the Sharia, it is not considered disbelief. One must repent to Allah and control their words, for a word can plunge its speaker into Hell. It is obligatory for spouses to live together amicably. It is obligatory for the wife to obey her husband in what is right and lawful. The husband is permitted to discipline his wife by admonition, then by abandoning her in bed, then by striking her without causing injury, if needed, though it is preferable to refrain from it even when permissible.