Partisanship is good. We jump out of bed, brush our teeth, comb our hair, pluck our navel lint and saunter out into the great wide world perfectly and honestly prepared to consider each and every new proposal for societal change that presents itself to our entirely open minds. We wouldn't be able to think, much less govern, our way through a week. Life is chaos, and the first order of government is to impose order on chaos. A moral government imposes a moral order, which is to say, the order of the wishes of the majority, tempered by the needs of the collective and the rights of the minority.
Moral government rests absolutely upon partisanship.
In a nation of democratic impulse, the people naturally, eventually, sort themselves out. As the people coalesce around their choices, they naturally give rise to mass ideologies. Political parties naturally form to express and institutionalize these ideologies. Between the opposing parties, there is naturally a fight. One ideology-party, representing at least a plurality of the people, triumphs and reigns for a period.