The reason doesn't matter. What Kevin did was both good and bad.
Um, no, that's kind of the point of the thing. What Kevin did was bad; but it was an act of extreme desperation. He gave in to despair. This is one of the central themes of the entire series.
That's not accurate at all. Thomas is the unbeliever. I suppose you could compare this to something like the AA notion of believing in something greater than yourself. The Ur-viles don't have a problem with belief; they are simply evil.
That is either a gross misrepresentation or complete ignorance. The Ur-Viles are not simply evil, but are far more complex than that. You clearly haven't read much beyond the First Chronicles, since the Second Chronicles begins their re-evaluation of their Weird, and the start of their redemption; which comes into culmination in the Final Chronicles. Their problem is entirely one of belief and interpretation.
Fallen in what way? They were described as self loathing because they couldn't see.
This is not even remotely close to accurate. They are describes as self-loathing due to the inheritance of their nature from their predecessors, and the influence of the Ravers. The Viles turn to loathe themselves because of their incorporeal nature and separation from the world, and their obsession with introspection; which allows the Ravers to poison their minds and convince them their unformed and detached beings are flaws rather than simply their own nature. The Demondim inherit their makers' nature; and are vulnerable to the same lies. Combined with the fact that they are only able to achieve corporeal presence through Possession (treated throughout the series as an unalloyed evil), specifically possession of the dead. Like the Viles' detachment, this effectively locks them into self-loathing and despair.
The Ur-Viles and Waynhim, being constructs, are also separate from the natural world of the Land, and through that are also influenced by the Ravers; though being less potent beings than their predecessors, are thereby less vulnerable (thus fitting into the central theme of power and guilt). Though essentially the same beings, they are more able to choose how to respond to their self-loathing; with the Waynhim choosing to redeem themselves in service; and the Ur-Vile to embrace destruction at first, then later changing their path to one more approximating that of the Waynhim.
In all three cases, the beings did not start out as evil. They started out as essentially neutral, but unnatural. It is their lack of connection to the natural material world that is the seed if their despair and descent into self-loathing via the poisonous influence of the Ravers. Each creation was intended to redeem this state by creating a link to the natural material world. That this fails repeatedly is due to the incompleteness of their attempts, a lack of understanding of the earth and Earthpower, and again, the influence of the Ravers. It is the redemption of the Ur-Viles that they are finally able to throw off this influence and dedicate themselves to the service of the Chosen to the degree that their Weird allows; much as their Waynhim cousins did.
This behavior is not surprising in the character. It is also not really something you can blame the character for. Do you not recall that he tries over and over to test the reality of the Land and fails each time?
It's not his refusal to acknowledge the physical reality of the land that's the problem; it's his refusal to accept it's reality and importance
for him that is the base of his problems in the first two books, and the problems he causes because of that.
I don't know what you mean by that phrase. What does saving a life have to do with petting a dog?
It's an idiom referring to a defining act of goodness by someone who up to then had expressed only some form of badness or detachment. It's commonly used as a contrast to "kick the dog".
No. There is no redemption. There is only service and acceptance. This theme is made several times in the book.
You're clearly not reading the entire thing. I strongly recommend you read the entire series (which was finally completed last October), since you are missing some of the most crucial themes underlying the entire worl.
I disagree. In the 3rd book, he seems to acknowledge that the Land is real. However, I don't see the notion that he sees himself as necessary until the second trilogy when he repeats the phrase, "you are the wild magic."
This is quite clear in his confrontation with Lord Foul at the end of the first book. I don't know how to explain it to make it any more clear.
You seem confused. His final confrontation with the Despiser is in book 6 whereas Foamfollower dies in the first trilogy.
You're either misremembering or not understanding. Each Chronicles concludes with a confrontation, none of which is truly final until the end of the Final Chronicles. The concluding confrontation in the First Chronicles is the apotheosis of his search for redemption; his acceptance of the Land as important for him and release from his own mental prison. The confrontation at the end of the Second Chronicles is his acceptance of his importance to others besides himself, and epitomizes his own self-sacrifice -- something he had hitherto avoided -- both for the people of the Land, and for Linden. The Final Chronicles I'll let you read for yourself, since you clearly haven't.
Erm, no it's not; it's the world of the author himself. Can you explain why you think it's false, or is this just a bare assertion you can't support.