Wit tells two stories simultaneously. Both stories deal with the search for God. Inside the hospital the director shows us the accomplishments of the talented oncologists at the top of their field searching for God in their attempt to heal. Next to the doctors there is the compassionate nurse who gets closer to God through her loving care.
The movie cuts back to another identical search this time at the prestigious university where Vivian studied as a young woman. It shows the top students and professors searching for God in the sonnets of the highly intellectual poet John Donne. For people unfamiliar with his work ALL of Donne's poems and sonnets (they're gonna hate me for this) can be reduced into the most complicated game of Finding Waldo.
In all of Donne's work he very shrewdly hides God somewhere inside his poems. But it takes the skills of the sharpest intellectuals to break down his poems to find where he has hidden God. There are scholars who have dedicated their entire career to analyzing John Donne. The movie focuses on one particular sonnet: Death Be Not Proud. Wherein Donne has hidden God in the punctuation holding the last two clauses together. In fact another appropriate title for the movie could have been "Comma".
The last scene of the movie shows her at the hospital in great pain being visited by her old professor.
When she asks Vivian shall I recite to you something from John Donne? Vivian cries NO as if that would only increase her pain and is not what she needs now. And instead they find God together in a children's story called The Runaway Bunny.