What does "Making Mischief" mean in Islam?

According to  "A Dictionary of Modern Written Arabic (3rd ed.)." Spoken Language Services. p. 712, written by Hans Wehr and J. Milton Cowan, the word "Fasad" (Arabic: فساد‎‎ /fasād/) is an Arabic word meaning rottenness, corruption, or depravity.  In some English translations (Yusuf Ali, which is the most popular English translation, but also the Shakir and Mohsin Khan translations), it is translated as "Making Mischief." Translator Muhammad Sarwar goes so far as to translate it "to spread evil."

The word is used in Surah 5:33 of the Qur'an (which, ironically, immediately follows the most commonly misquoted verse in the Qur'an, 5:32, which you can read in its entirety HERE) and the punishment for Fasad is described in great detail. 

Surah 5:33 Indeed, the penalty for those who wage war against Allah and His Messenger and strive upon earth [to cause] corruption (Arabic: فساد‎‎ /fasād) is none but that they be killed or crucified or that their hands and feet be cut off from opposite sides or that they be exiled from the land. That is for them a disgrace in this world; and for them in the Hereafter is a great punishment,

What is the punishment for Fasad? Death, crucifixion, or dismemberment, or exile.  Indeed, the punishment is ONLY this... that is, there can be no other form of punishment.  Just one of these four.

Can anyone commit Fasad without knowing it?  According to the Qur'an, yes.  

Surah 2:11-12:
   11.      When it is said to them: “Make not mischief on the earth,” they say: “Why, we only Want to make peace!”

   12.      Of a surety, they are the ones who make mischief, but they realise (it) not. (sic) (Yusuf Ali translation)

Who are the ones who commit Fasad?  They are the ones who say they want to make peace.  Are they being dishonest when they say this?  No, because according to the Qur'an, they don't realize the error of what they are saying... that is, they are sincere.  

If you are a Christian, and you teach other people that Jesus Christ was Crucified, died, and was raised to life on the third day, you speak against Qur'an 4:157, which you can read HERE.  If you do this, you "cause corruption" or "make mischief." 

What does the Qur'an tell Muslims to do to you?

How does that make you feel?