Salam Alaikum,
I was speaking yesterday with an atheist, and the main discussion was about "How can you be sure that Quran is 100% not altered between the moment when Djebril Alayhi Salam gave the message to Prophet Mohamed Salla Allah aalayhi wa salam, and when Prophet Alayhi sallat wa salam gave it to his camarads" ?
How to be sure that Mohamed did not forget even one word..etc
My answer was : If he forgot something, it was easy for Allah to give corrections !
Can someone give me additionnal "proofs" or answers please