This poem, like many of Sir Walter Scott's poems, reflects a deep love of the Scottish land and the way that so many battles were fought in defence of the liberty of Scotland. The bold title of the poem of course focuses us directly on the theme of patriotism and the intense love of one's land and country, adn the first few lines immediately pick up on this theme by arguing that there can never be a man "with soul so dead" that he is not able to wonder at and appreciate his "native land." The speaker continues by imagining that there can neither be a man whose "heart hath ne'er within him burn'd" when he returns home after being away from his country.
If there is such a person, the speaker, says, no matter how important he is and how wealthy he is, he is still a "wretch," who shall "forfeit fair renown" through his lack of patriotism. If such a person were to die, he shall die "doubly," as the final lines of the poem make clear:
And, doubly dying, shall go down
To the vile dust from whence he sprung,
Unwept, unhonour'd, and unsung.
Lack of patriotism is clearly equated with a kind of grevious sin that will result in the series of negatives that are emphasised in the last line through the repetition of "un.." Clearly, to not be patriotic is a terrible crime in Scott's book.