I have written a great deal about Muhammad and the Quran, the summary of which is he was a liar not a prophet.
One reason I knew this from my first reading of the Quran is the horrible verses about hellfire and the torture of unbelievers for all eternity.
I had been quite sure that hellfire does not exist for a long time before reading the Quran. It is obvious that Muhammad stole the idea of scaring people with hell from the bible, which is also largely bunk. The spirit world teaches there is no hellfire, and no Satan, and there will be no judgement day.
The Quran also says the sun has an orbit, and it Is certain it means the sun orbits the earth. Imams lie and say it means the sun orbits the galaxy, but there is a hadith that explains what Muhammad thought about the sun, and it is clear from this hadith he thought it orbits the earth.
There are also clear falsehoods in the Quran that have been stolen from other sources. Such as the story of Jesus bringing a clay bird to life when he was a boy. This story appears twice in the Quran, but its source is a known book of fables called 'the infancy gospels'. Muhammad stole this story even though it is not from the bible but a book of myths.