The antithesis to the sun rising god (inspired knowledge) are the flames of man (Promethian).

The fact that the holy knights weapon is named after a 'good' god while Squall is related to 'evil' gods (fenris, lone wolf and the luna cry) is another hint to the nature of things.

Big D - Seifer often lacks sympathy and does some pretty regretable things (bombings, killing) but he does this to preserve tradition. Seifer aimed to bring religion back into the world. This is why he makes secular Esthar his main target (and naturally for economic reasons too!)

Squall on the other hand is liberating, he supports people and not to forget, he is also the players access point in the drama. However, do not be fooled by the sheep in wolves clothing Sqaull is all about the defiance of god. He shuns the moon (the great hynes realm) he attacks the gods representatives edea, ulti and adel.
He also acts as an extention of Laguna; the man who brought about a revolution to end religion in Esthar - and then the luna cry (armageddon) occurs as a result of Esthars irreverence! So what is so bad about this? Well religion plays an important role in culturing the human beast. All nations that have eliminated religion in world history have collapsed! Russia is the best 'real world' example of 'Esthar' as it was technological, socially equal and it lacked a religious identity. All philosophers agree that religion is the source of morals and ethics and without this framework a human does not develop fully. i.e. the 'memes' for virtue and good behaviour are not present.

A more refined version of Squall Vs. Seifer is witnessed in the film "Blade Runner". This is an early 80's film which pits the tall, blond idealist Roy (Rutger Hauer) against the dark and passive Deckard (Harrison Ford).... Note: I do the film no service with simple descriptions of the leads; this was only to demonstrate the 'theme' of the two rivals in other media.
In the end if your not convinced on all the contextual stuff or your a bit of a nihilist; allow me to state the dry facts as I see them - Roy and Seifer kill for principles so they are 'good' as they sacrifice themselves, whereas Squall and Deckard 'evil' as they kill for a job to fill personality defects.
Now for the twist - Squall and Deckard do However experience Gods virtue... In the final scene Squal and Rinoa kiss under the moon light (the Hynes realm) and Deckard witnesses a pure white dove. These are some interesting contradictions, indeed.