The Quran is sacred to the Muslims. We believe this is the words of Allah (swt). Allah has instructed us that in our 5 daily prayers, our prayers would be incomplete without it.
We believe in the sunnah and hadith so if anyone was to disrespect them, it hurts us. Allah (swt) tells us in the Quran do not mock or swear at those who worship others besides Allah.
The thing we may consider absurd to worship, but it is very dear to them. We can disagree but offer them a certain level of consideration when engaging with them.