The Christian idea is that we inherited our sins and need to believe in somebody who died to get us out of them.
Dogma was typical of thoughtful movies about Christianity in that it raised uncomfortable questions about scripture, and did it while getting the scripture right. And also typical in that most Christian organizations hated it.

One of my favorite parts was the statement from Rufus[1] that the problem with modern Christians[2] is that they have a belief, but what Jesus taught was an idea. "People will die for a belief, or kill for it. But they can discuss an idea."

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[Edit] Found the actual quote:
Rufus: He still digs humanity, but it bothers Him to see the shit that gets carried out in His name -- wars, bigotry, but especially the factioning of all religions. He said humanity took a good idea and, like always, built a belief structure on it.

Bethany: Having beliefs isn't good?

Rufus: I think it's better to have ideas. You can change an idea. Changing a belief is trickier. Life should be malleable and progressive; working from idea to idea permits that. Beliefs anchor you to certain points and limit growth; new ideas can't generate. Life becomes stagnant.

...

A belief's a dangerous thing, Bethany. People die for it. People kill for it.


[1] The 13th apostle, played by Chris Rock.

[2] They focused on Catholics in the movie.