Why is Melkor so utterly evil??

[Bruce MacCulloch]

Quoth Mhoram:

I don't think that he was evil to start with, but he was proud.

Most of the great 'downfalls' in Tolkien's works can be traced to, if not pride in general, at least to arrogance. Morgoth's pride in himself led to his turn to evil, Gondolin's fall can be traced to the pride of Turgon in ignoring the warning of Ulmo, Nargothrond fell because of their pride in their strength, Smaug was killed because of his arrogance in showing off his 'waistcoat', Saruman's arrogance in attempting to vie directly with Sauron led to his ensarement, the list could go on. It seems that Professor Tolkien firmly believed in 'Pride goeth before a fall'.