how much do theological views matter to everyday life?

I wonder about the extent to which working effectively to "fix the world" is correlated with accurate theological views. (I like C.S. Lewis' observation that we're all theologians. The question is whether we're good or bad theologians.) Can one be much more effective with accurate views in this context-- or it doesn't matter all that much? Could one be profoundly wrong about theological matters and accidentally stumble into greater effectiveness?

To stir the discussion a bit more: In three consecutive comments below, I'll link two blog posts and an article about certain versions of theism (a recent anecdote from my life), deism (of the "moral therapeutic" variety), and atheism (a "Sunday School" class of atheists that I attended a few years ago)-- as one example among various types of each.

Thoughts?