Bismillah i-rahman i-rahim
In his book “The Divine Reality”, Hamza Tzortzis writes:
The Prophet Muhammad ﷺ experienced many trials and tribulations during the course of his Prophetic mission. For example, his children died, his beloved wife Khadija passed away, he was boycotted, his close companions were tortured and killed, he was stoned by children, he engaged in military campaigns; throughout all this, the Qur’an’s literary nature remains that of the Divine voice and character. Nothing in the Qur’an expresses the turmoil and emotions of the Prophet Muhammad ﷺ. It is almost a psychological and physiological impossibility to go through what the Prophet ﷺ went through, and have none of the resultant emotions manifest themselves in the literary character of the Qur’an.
Someone might argue: “Well, this only shows that Muhammad wasn’t the author. It doesn’t mean God is. After all, someone could have been writing it for him who wasn’t experiencing the same suffering.
But Tzortzis points out the absurdity of the Qur’an being authored by a human other than Muhammad (saw), writing elsewhere in the same essay:
If an Arab other than the Prophet ﷺ had produced it, he would have had to constantly shadow the Prophet ﷺ wherever he went, and spew out revelations whenever the occasion called for it. Is one seriously to believe such a fraud would go unexposed for the entire 23-year period of revelation?
The Qur’an was either from man or from Allah. Having exhausted the former option, we are left with the latter as the only plausible explanation.