

I actually rewatched it tonight and I’ve changed my mind that the “power corrupts” theme doesn’t go anywhere. On a second viewing (where I could concentrate 100% without someone eating popcorn loudly in my ear) I thought there was actually quite a well rounded arc built around that theme,
spoiler
with the conclusion coming when Lawrence admits to Bellini he has considered his own papacy and finally succumbs by voting for himself. The suicide bombing occurs right as he casts his vote, and acts as a symbolic intervention from God in response to his sin.
Aside from distraction in the cinema and the benefits of a second viewing, I think the reason I overlooked this the first time around is because it is immediately followed and perhaps overshadowed by the multiple plot twists involving Benitez, who until then hasn’t featured much in the film. Originally I thought his story didn’t really tie in with that of Lawrence, and I still think it is underdeveloped considering the ending of the film, but now I can see that if Benitez represents innocence then the ending of the film is really about Lawrence coming through a trial of his faith and the temptation of sin to rediscover this.
I don’t think that aspect of the film is actually relevant to the central themes or story, though.
spoiler
The terrorist attack is more of a plot device to break the isolation of the Conclave, and thus to bring the cardinals back from the temptation of power and to remind them of the greater world and the people they are ultimately in service to, as well as to setup the final confrontation between Tedesco and Benitez.