Quran is the word of Allah . It's neither deficient or incomplete. It wasn't altered by anyone, It's preserved in the "preserved tablet". It's not created.

You can't say I don't know. You must have the Aqeedah that it's the word of Allah .

Narrated Abu Hurairah رضي الله عنه:
The Prophet ﷺ said, "When it is a Friday, the angels stand at the gate of the mosque and keep on writing the names of the persons coming to the mosque in succession according to their arrivals. The example of the one who enters the mosque in the earliest hour is that of one offering a Camel (in sacrifice). The one coming next is like one offering a Cow and then a Ram (Sheep) and then a Chicken (Hen) and then an Egg respectively. When the Imam comes out (for Jumu'ah prayer) they (i.e. angels) fold their papers and listen to the Khutbah."
Saĥîh Bukhârî

Sahl b. Sa'd (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:

In Paradise there is a gate which is called RAYYAN through which only the people who fast would enter on the Day on Resurrection. None else would enter along with them. It would be proclaimed: Where are the people who fast that they should be admitted into it? And when the last of them would enter, it would be closed and no one would enter it.

Sahih Muslim, 1152