Prophet Muhammad(saw) had 40 years before being declared a prophet to show his character and he was labelled the truthful/honest.Plus he was illiterate
The Quran has many scientific and historical and linguistic miracles
Ill give a few .Linguistics wise the quran is amazing in Surah Baqara God says if you think this is from a man then produce a chapter like it. The shortest chapter in it is 10 words which has approximately 40 literary techniques in arabic i've only counted 24 in english, but nevertheless still amazing.
Historically the King at the time was called a Pharoh in the Quran during the time of Moses but during the time of prophet yusuf(joesph) the king is known as king which is confirmed by a recent historical discovery
Scientifically the quran talks about the big bang which is pretty awesome and that water is the origin of life
“Have those who disbelieved not considered that the heavens and the earth were a joined entity, then We separated them, and made from water every living thing? Then will they not believe?” (Quran 21:30) Also it tells that the universe is expanding which is a recent discovery "
“And the heaven We created with might, and indeed We are (its) expander.” (Quran 51:47)"Then Jesus(saw)submitted his will to god which is the very definition of a muslim and prayed ,fasted,was circumised and so on.I mean who else could know this ? An illiterate man in the dessert couldn't know this , only the creater could. This is the only the tip of the iceberg .God who we call Allah which translates to "the god" like Elohim in the bible has sent over 100,000 messengers to the whole earth and the Aboriginal tribes had a concept of an Eternal supreme being which matches the description of the quran in the bible . look here
The Concept of God among the Aborigines of Australia press ctrl f and search for the words god. We belive Jesus Christ and we believe he is one of the best men to ever walk on this Earth and u cant be muslim unless u believe in Jesus christ.However Jesus christ never claimed divinity but rather he said " the father is greater than i " meaning Jesus could not be the father and hence Jesus doesn't equal the father.But the church teaches a concept of trinity a term which is non-existent in the bible.
There's so much but yeah the quran even reasons with us telling use ur logic in conjunction with scientifc facts only being discovered recently.It truely is a miracle and based on the prophet's character he was a honest person and even the person who poisoned him he forgave her but we dont worship the prophet.He's just a slave. Just like jesus was. God is testing us and yeahh... its a deep story