I won't try to speculate as to what Brando was attempting. At his best he turns in such oddball performances, insinuating so many things at once, that it doesn't seem he does anything so much as play by unfailing instinct. Often it seems he is calling attention to some favored aspect of his character over all others, a concentration which, if followed, turns out something of a red herring, as he turns out subtler, craftier than at first appeared. This is a mastery of artifice, not naturalism, as might be associated with the Method. The role of Sky Masterson, as Mankiewicz so wonderfully realized, seems tailored for him, which is to begin with odd, and odd still at the end, because whatever it is Brando has done, he has managed a grace maybe all his own, but a consummate grace nonetheless -- again, odd, coming from an actor with limited musical ability, not ever before or after associated with the musical comedy. Jean Simmons, also oddly cast, is not quite as impressive, but certainly above just-adequate, really delightful in the Havana sequence, and never less than enjoyable throughout.
And yet...perhaps because actors are both so concentrated on what it is they are doing, and characters on what it is they intend of each other, there doesn't seem to be the lovers' "chemistry" brought up so insistently more than once. Brando/Sky Masterson and Simmons/Sister Sarah respectively feed off one another well enough, but I for one don't see more beyond that. In a movie this outrightly dazzling and entertaining (and most everything about it, craft-wise, is just that -- dazzling), that lack would seem something tactfully and easily overlooked, but so much would depend upon true chemistry! An, at least partial, transformation of the characters through such chemistry, would lend something positively moving to the final scene. As it is, one leaves this film certainly delighted, but not really moved, except in a way as to negate the trueness of the union. Note Sister Sarah marries in her missionary's uniform, Sky Masterson in his same natty man-about-town duds rather than wedding tux. And they have changed back to those from their previous scene!
Funnily enough (that is, insightfully), the most touching, and most serious, scene is, I think, between Brando and Vivian Blaine, as Sinatra/Nathan Detroit's doll, Adelaide, the only scene where these two are exclusively together, not least because there is just no hint of flirtation between them even though it takes place in Adelaide's dressing-room while Adelaide is about to change. Though one may submit there is no place for that, Sky really is the type to "check out" Adelaide in this sort of circumstance. He is even there to tell Adelaide Nathan will not be meeting her to elope. Adelaide and Sky are both true in their respective ways to Nathan, even piteous of him, as is demonstrated through a tone in their exchange. Adelaide is of course also frustrated and disappointed, but her anger is mitigated by her deeper feeling for Nathan, as Sky is admonishing her that she can't love a man and then wish him to be someone else.
Guys and Dolls is another turn at the battle of the sexes, around the themes of gambling and salvation. Since both the compulsive gambler and the salvation seeker are more or less unconsciously courting despair, there just may be a dark secret deliberately behind Brando's and Simmons' lack of chemistry. After all, that lack may well denote an excess of narcissistic preoccupation (echoed by the Sinatra/Blaine pairing, though with considerably less self-deception involved), which might explain Brando's and Simmons' odd, rather provoking, interpretations of Sky Masterson and Sister Sarah. I realize Simmons may be mostly depicting coldness and skepticism, but Brando, though playing to confront her, isn't exactly heated and eager, and is more than keeping his distance -- he's also assimilating it, keeping his balance through it. His boldness consists in merely playing against her -- the trip to Cuba, a kiss, whatever it takes -- but he is not actually set on winning through seducing her so much as beating her then in her own turf. This may be shrewd, as playing to zeal may be the only way to get to the missionary, and through. But it makes Sky's transition from merely trying to win a bet to actually wanting Sarah Brown a little less than persuasive. Yet why does he want her? What does falling in love mean to Sky? I find the only way to get around this is by indeed accepting his humanity has kicked in, and that he does not want to end up a mere cad toward Sister Sarah, so he does, as he's promised her, need to deliver the sinners to her prayer meeting, make good by his "marker," as he puts it, as a way of winning her back when it seems he had already won only to lose her. But this still denotes self-concern more than anything. However, it also allows for Sarah Brown's own self-concern, as Sky will placate the missionary in her in order to get back the lover. Neither, at least it seems, will change much by their union, except perhaps in the acceptance of the other. Yet that would seem an all but fatally uneasy proposition: acceptance of is still quite a cry away from achieving happiness in the other, let alone the transcendence they each seem to imply by "chemistry." And behind all this, I suspect is Mankiewicz's full knowing.
For all those who might say, in defense of Guys and Dolls yet, that not much can be expected from musicals by way of depth, I need only remind them Cabaret, The Three-penny Opera, Carousel, A Star is Born, even The Sound of Music, which I don't care for as much (and one can keep adding to this list without even reaching forward toward post-Cabaret musicals), all wrap gorgeous music and dance around dire anxieties.

I have been using IMDb for years and I never wanted to get involved in the commentary of moviesuntil now. This documentary has so many problems that I hardly know what to say. I am not a Muslim, nor am I an Islamic studies expert, but I know enough to shed some light on the obvious one-sided viewpoint that this documentary espouses.
The problems with this movie begin with the fact that it is a documentary. Most of the documentaries that I have seen anchor themselves around a few valid points and then surround those points with debatable interpretations and misinformation. This is certainly the case with Islam: What the West Needs to Know. Yes, there are fundamentalists around the world, and some of them are Muslim, but to build a documentary about all of Islam around a small percentage of radicalized people is incredibly misleading. This is really a documentary about the fundamentalist aspects of Islam and nothing more.
For those who would like to more objectively explore some of the issues raised in this documentary, here are several points that may help.
There was nothing positive about Islam presented in the documentary.
The documentary focuses on the Middle East, but more Muslims live outside of that region. More Muslims live in China, believe it or not, than in Saudi Arabia. About 40% of all Muslims live in Pakistan, Bangladesh, India and Indonesia.
The translation of the Qur'an used in the documentary is a questionable one. I watched the documentary while viewing another translation and the differences were striking. I had been warned about the translation that was used in the documentary and now I know why. Surrah 98:6 is a good example. The documentary suggests that the Surrah says that disbelievers will go to hell. But the translation I have reads instead: "Those who reject Truth among the People of the Book and among the Polytheists will be in hellfire." The difference is that those who reject Truth are those people who know about God and the Truth of God and decide to reject it anyways.
The movie mentioned that there is no morality inherent in Islam, but this is not true. Although it is true that much comes from the Qur'an and Hadith, Islam also recognizes a concept called 'Urf or "normative behavior." Obviously what is normative can be interpreted many ways, but 'Urf is meant to be "good" behavior, what an average person would consider right or wrong.
The documentary presents Shar'ia (Islamic Law) as being one unified body of knowledge that all Muslims follow. This is simply not true. There are many Islamic schools of law and they range from progressive and modernist to fundamentalist in the way they interpret law.
The Hadith tradition is similar. There are thousands of Hadith and each school of law accepts some and rejects others. Using the Hadith without serious scholarship to determine which ones are accurate, real and applicable, is indiscriminately picking and choosing quotations from history that fit what you want to say which is what the documentary did.
What I hope people realize is that fundamentalism is the problem, not Islam or any other religion. Christianity has fundamentalists that shoot abortion clinic doctors and so on. I know this is not the same as suicide bombing, just understand that the righteousness of fundamentalism is arguably the problem. If you feel you have THE answer, then everyone else must be wrong. But if you feel you have AN answer you can work together with other people's views about politics, religion, God, or whatever.