MashAllah, very good explanation brother BigAk, brother Hamzah and brother Ayman.
Surah al-Isra', 17:88
Say: "If the humankind and the jinns were together to produce the like of this Quran, they could not produce the like thereof, even if they helped one another."
Surah Hud, 11:13
Or they say, "He (Prophet Muhammad) forged it (the Quran)." Say: "Bring you then ten forged Surah like unto it, and call whomsoever you can, other than Allah (to your help), if you speak the truth!"
Surah Hud, 11:14
If then they answer you not, know then that the Revelation (this Quran) is sent down with the Knowledge of Allah and that none has the right to be worshipped but He! Will you then be Muslims (those who submit to Islam)?
Surah al-Baqara, 2:23
And if you are in doubt Concerning that Which We have sent down To Our slave, Then produce a chapter like it And call your witnesses besides Allah, If you are truthful.
Surah Al-Hijr, 15:9
Verily We: It is We Who have sent down the Reminder (i.e. the Quran) and surely, We will guard it (from corruption).