Why did the Bene Gesserit want to breed the Kwisatz Haderach?

I would venture that in the early days of the Bene Gesserit, their motives were essentially religous: they considered the Reverend Mother State of Consciousness to be holy, and creating a "Reverend Male" would be equally holy - as well as a source of wisdom. I imagine this as their "We exist only to serve." days. But in order to try to positive influence the society in which they found themselves, they chose to move whenever possible into the political circles of the Great. When they began to breed with them, they created unanticipated consequences: they were breeding into themselves the genes for personal ambition, the will to dominate. Thus their plans for the Kwisatz Haderach shifted toward trying to create someone they could use to their own ends.