@airnautique,
Let me preface my remarks with a caveat, to the effect that i don't know what you've already covered in your course, or what your instructor has told you prior to presenting the assignment.
Premise One might be flawed in that it is possible that a "god" might be omnipotent and omniscient, but still reside in a cosmos which that god did not create. Therefore, I suggest that your first premise must be a definition of god. This could be, based on what you've discussed in class, a case of question begging if one defines god as the creator of the cosmos,
a priori.
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Premise Two seems rather extravagant in that "everything" is also not defined. Is that everything that we might imagine, or is there some limit on how everything is to be defined? Once again, without having taken the course, i can't know what your instructor has told you about this.
But there is another problem here, as well. There are two dichotomies which are often assumed to be identical, but which are not in fact identical. The first is the good/bad dichotomy. This is almost certainly going to be a subjective judgment: that which i like or which benefits me is good, that which i do not like or which harms me is bad. However, that subjectivity is implicit in the dichotomy, and we may, without suffering cognitive dissonance, accept the subjectivity, and accept contradictory judgments on this subject. For example: Joe likes to eat meat, and "knows" that eating meat is good for him; Mark does not eat meat, because Mark "knows" that eating meat is bad for him. We can accept both statements in the knowledge that they are subjective statements for which neither speaker has provided substantiation.
The other dichotomy is good/evil. In that dichotomy, both terms are assumed to be absolutes: good is assumed to be good in the eyes of all observers, and evil is considered to be evil in the eyes of all observers. (I would argue that this is a false dichotomy, or very likely a false dichotomy, in that the absolute nature of good in the dichotomy might be challenged, and the absolute nature of evil in the dichotomy might be challenged.) Therefore, at the least, good and evil need to be defined, and distinguished from the good and bad of the good/bad dichotomy. If good and evil are absolutes, there can be no disagreement on what constitutes good and evil.
(There is a rather elegant review of this subject--the good/bad dichotomy and the good/evil dichotomy--in Nietzsche's
Beyond Good and Evil.)
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Premises Three and Four are completely unnecessary, and, given that Premise One assumes the existence of god, a rather sad case of circular reasoning, if the point is to establish the existence of god. That ought to have already been assumed.
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The conclusion and Premise Five would be reasonable, if you can establish the first two premises.