Complex sentence: The in-universe motivation for the "Enlightened" faction is their belief that the Shapers are working toward a powerful enlightenment which will uplift all mankind, whereas the "Resistance" believes that it is protecting humanity from Shaper ingression.
Split into simpler sentences: The in-universe motivation for the Enlightened faction is their belief that the Shapers are working toward a powerful enlightenment which will uplift all mankind. The Resistance believes that it is protecting humanity from Shaper ingression.