(IronBeer has an internal dialogue as to whether he should join the fray... aw, sod it).
As a Catholic, I believe I may be ...erm, marginally qualified to comment on the efficacy and faults of organized religion. The way I see it, there are two distinct pieces to an individual's faith- their actual belief, and the religious community around them. Belief (the spiritual, individual part) is typically not too hard to come by (assuming the person in question is in fact faithful) or understand/ tolerate. It is the organized piece, the actual religion, the institution, that I see seems to be the biggest lightning rod. The problem (as I see it (could it just be understood from this point forward that most of what I say is as I see it?)) is that a debate about the spiritual component will invariably lead into debate about the institution. Disagreements over some of the finer points of belief are the reason so many sects of Christianity emerged (not in the mood to do research- I'm going off what info I can pull from the top of my head).
But here's the kicker- as beings of free will, us humans have the ability to make choices independent of God; the biggest ramification of this fact is that we are free to choose our belief system as we see fit. This is where the "institution" comes into play. I think it would be a good reminder to all involved that all dominant religions today essentially started as cults. This fact may come off as distasteful to some members, but it *is* truth. I'm not going to argue over the divinity of any cult/ religious figures from the past or present (not that the divinity of Jesus is a point of contention for me anyway), but simply point out that all of these people preached a gospel that people liked, to some extent. At its core, a "religion" is really nothing more than a community of individuals who share a similar spiritual outlook, and a set of beliefs as preached (generally) by some sort of leader figure.
The trouble with a "religion" starts to arise when it becomes popular (so to speak) and begins to attract large numbers of followers, and invariably, funding. There are so many examples of what I'm talking about that I don't think I need to point any out. And, since any religion is a human institution, there is a degree of falliability in anything the higher-ups may do. Religious wars, suppression of science, collection of wisdom, and charity- a well-funded religion can precipitate all these things and more. For all the good the institution does, approximately equal evils can be found- much like humanity as a whole. If "absolute power corrupts absolutely", then how much drive could a religious higher-up have if they believe, no.. KNOW that their actions are what God desires?
And, that, as I see it, is the crux of the whole issue. Without checks on their morality or egos, religious authorities can all too easily lose sight of what their faith is really all about: (for most religions) charity for the less-fortunate, love for your neighbors, community with fellow believers, and an intimate relationship with God. Despite my Catholic upbringing (and subsequent Confirmation), I give far more attention to the words of my church's relatively-grassroots priest, and tend to take proclamations from the Vatican with a grain of salt. The Pope and Cardinals are undoubtedly holy and wise men (to me, at least), but I do feel that their life in a place such as the Vatican may result in some degree of disconnection from the actualities of the issues facing my country.
But... as it stands today, I don't feel that religion is really holding back human advancement. I personally feel that the influence of organized religion in general, and in particular my own Church, is fading. Now, surely, institutionalized religion can't be holding us Terrans back if its power is on the wane? Yes, I'm aware of the zealots in the Middle East and the pain that religion has and is causing in that part of the world. I do, however, feel that repressive religion is beginning to lose hold in those parts of the world. Somewhat perversely, I can get behind a blossoming of freedom at the cost of religion- religion is, at is core, a personal relationship between one's self and God, and that should always be a conscious choice.