If you're searching for film titles that explore the question "What is Christianity?," the list is fairly inexhaustible if all English and non-English films are considered.

However, here are a few titles in which the subject was tackled by big directors that I can think of immediately:

The Song of Bernadette (1943)

The Last Temptation of Christ (1955)

Brother Sun, Sister Moon (1972)

Francesco (1989)

The Seventh Seal (1957) -- actually many films by Ingmar Bergman dissect the fundamentals of Christian faith

The Gospel According to St. Matthew (1964)

Christianity it's mean by follow to Jesus Christ!

Christianity is an accepted form of gambling, to a christian it is a sure thing that Jesus is going to pay them off with angel privileges or something, but in fact we are all dammed to hell.....what I say is for each of us to embrace the good as best we can, we people are basically good, but of course there are some rotten eggs that will cost us all in the end. The bible says: "we people in this plain of existance are the envy of angels", so walk your talk.

My idea is for everyone to tithe in a new way, every day each of us should drive or walk or just do this: through seven aluminum cans along a road somewhere, not in the garbage, that give away could turn the whole economy around in seven years.