According to Paul, the community's problems were the consequence of the Corinthians' mistaken belief that they had already been exalted. They failed to take seriously the power of evil; their behavior caused divisions in the church and led to a lack of concern for other members.
With respect to the question of who Paul's opponents were, there are three current answers: (i) some kind of Judaizers, (ii) some kind of Gnostics, or (iii) something like Georgi's suggestion.