[Lord of Angmar]

Cardinal Virtues and Deadly Sins, in any form, are platforms of Western theology, and Tolkien, as a Brit, would naturally imbue his own works with such pillars of the common world ideology. While it does seem in some instances that certain sins are particularly magnified and represented within Middle Earth (pride is a good example), it would be said by many that it was just Tolkien's way of thinking as a member of modern society that endowed his stories with examples of the Virtues and Sins.

I think Iluvatar knew well in his all-encompassing mind what actions and thoughts were to be considered 'evil' and 'sinful' within his realm, and that these sins are close if not identical to the idea of sins in Christianity, since Tolkien, being raised as a Catholic was inherently inclined to see these as the definitive evils of life.

Engaging in analysis of Tolkien's representations of evil and sin is by no means a waste of time, but the only question that seems to need answering is whether Tolkien thought specifically of the Seven Sins and the Cardinal Virtues when he wrote of Middle Earth. In my mind, a man's work can only be a representation of that which he knows, no matter how hard he tries to avoid symbology and allegory. Since the Deadly Sins and Cardinal Virtues are an extremely critical part of everyday life (the media, the judicial system and life in general all exemplify what is considered 'good' and 'bad'), and thus they are the simple and recognizable basis for almost any piece of fiction.