[He can handle SEELE being mocked. He did enough of it himself.]
The Human Instrumentality Project. SEELE saw it as the next step in Lilim evolution. [He forgets about his planned vocabulary change when he gets into talking seriously about his world.] If an Angel were to merge with its father, Adam, it would create a massive anti-AT Field that would strip all Lilim of their physical forms and reduce them to their most basic form - a single being that would hold every consciousness as one. There would be no more fear of closeness, no more pain and loneliness, because all Lilim would be one. Or so SEELE claimed.
SEELE and Ikari both wanted to control and manipulate events to create their own perfect Instrumentality. That's where the conflict came from.