Why is Shaitan bad considering the definition of the term?

Question

As per definitions that I have found on internet Shaitan is:

In the Koran an angel of high degree who was expelled from heaven because he refused to worship Adam at his Lord's command; often regarded as equivalent to Iblis.

Why is this considered bad in Islam (Ok, he went against God's command, but he must have had his reasons..)? How did we get from an angel that refused to worship to Adam to an entity/daemon that causes havoc and evil and that is feared by all humans and believers or various religions?

I understand that this was ordered by God, but to turn him from an angel to an Evil being is a little difficult to comprehend. Could someone shed light?

Actually I think he understood really how we humans are and that is why he made this choice.. (For reference I am not a Satanist, just a curious person)

Answer 1

First of all, shaitan/satan/iblees was never an angel as angels never disobey Allah. Here is clear evidence from Quraan:

And [mention] when We said to the angels, "Prostrate to Adam," and they prostrated, except for Iblees. He was of the jinn and departed from the command of his Lord. Then will you take him and his descendants as allies other than Me while they are enemies to you? Wretched it is for the wrongdoers as an exchange. Surat al Kahf : 50

Secondly, as you can also see from the verse, they (the angels and satan) were ordered to prostrate to Adam and not worship him. This prostration was out of respect to the new great creature that Allah created, not out of worship, as the only One Who is eligible to be worshipped is Allah Almighty.

And the reason for Allah's anger on iblees was not just that he disobeyed him. Besides that, he also showed arrogance, which is an Attribute that no one can share with Allah, as He is The Only Arrogant. Iblees denied Allah's great creation and despised it.

As for the reason of iblees denying mankind, he thought that our basic creation which is clay made us lower than him (iblees) who was made from fire :

[ Allah ] said, "What prevented you from prostrating when I commanded you?" [Satan] said, "I am better than him. You created me from fire and created him from clay." Surat Al Aa'raf : 12

After iblees was cursed by Allah, he made a promise that he'll try to take all humans to hell with him:

[Iblees] said, "By your might, I will surely mislead them all. Surat Sad : 82