It was G'Kar I believe... in season 5 (Meditations on the Abyss) giving his students a lesson about his take on God and the universe:
"If I take a lamp and shine it toward the wall, a bright spot will appear on the wall. The lamp is our search for truth, for understanding. Too often we assume that the light on the wall is god. But the light is not the goal of the search, it is the result of the search. More intense the search, the brighter the light on the wall. The brighter the light on the wall, the greater the sense of revelation upon seeing it. Similarly, someone who does not search, who does not bring a lantern with him, sees nothing. What we perceive as god, is byproduct of our search for god. It may simply be appreciation of the light - pure and brighter. Not understanding that it comes from us. Sometimes we stand in front of the light and assume we are the center of the universe. God looks astonishingly like we do. Or we turn to look at our shadow and assume all is darkness. If we allow ourself get in the way, we defeat the purpose, which is to illuminate the wall in all it's beauty and in all its flaws and so better understand the world around us."
G'Kar