All gods are aspects of the same God
"All gods are aspects of the same god" is a proposition that some more liberal theists use to explain away the Argument from inconsistent revelations. It is commonly stated by Hindu and New Age believers, as well as by apologists who are no longer strongly associated with a particular religious tradition.
One can see that Islam, Hinduism, and Christianity often use similar arguments and psychological tricks, but that none is particularly more convincing than the others. Most believers are either unaware of this problem, or ignore it, or argue that some particular argument works better for them than for other religions. Alternatively, an atheist concludes that they are probably all wrong and disbelieves in all gods until one religion comes forward with more convincing evidence.
However, some liberal theists, particularly those with misguided multiculturalist intentions, often try to take the reverse tactic and believe that every religion is true. Often these same people will claim that criticizing any particular religious tradition (or stating that any particular one is superior) is a form of religious intolerance or bigotry that denigrates others' beliefs.
These people are then in a bind, where they can't accept every religious statement that comes along without being extremely gullible and/or seeming to pick favorites. On the other hand, they can't reject these statements without feeling bad about "denigrating" other people's beliefs. They are consigned to a sort of murky assent, where they claim that somehow, perhaps "mysteriously", all the things that different people believe are true, despite how bizarre many of these claims are.
Blind men and the elephant
The blind men and the elephant is a parable about subjective experience and how peoples' experiences are not necessarily contradictory. It imagines several blind men attempting to describe an elephant without seeing the overall animal. Each man forms a different impression of the elephant, depending on the area that has been experienced. One thinks the elephant is snake like and hangs vertically, another believes it is hairy and rough and yet another believes the elephant is hard and smooth. The contradictory accounts of the elephant causes much confusion between the blind men. In some versions of the story, they begin to collaborate to understand the elephant more fully. 
The intent of the story is that different religious experiences are not necessarily contradictory, since they have only experienced one aspect of God or spirituality. Arguably, there could be a single objective truth but everyone is different and therefore experiences it differently.
The religions themselves are incompatible and intolerant
First off, it should be noted that almost any pair of traditional religions you care to name are on some level incompatible with each other. Hindus may be willing to accept a lot of different gods, for example, but for that very reason Hinduism is incompatible with every major Abrahamic religion. This is true not only in the sense that they tell different stories, but also because their moral commandments and practices are in direct opposition. When Yahweh demands that only he may be worshiped and repeatedly commands his followers to drive out and kill worshipers of other gods, destroying their temples and religious artifacts in the process, that's not a trivial inconsistency.
- "Indeed, as the pastor realized, religious beliefs cannot all be true, because many religious beliefs are contradictory-they teach opposites. For example, conservative Christians believe that those who haven’t accepted Christ as their Savior have chosen hell as their ultimate destination. It’s often overlooked, but many Muslims believe the same about non-Muslims-they’re headed for hell as well."
The truth is, religious intolerance of one form or another is part and parcel of most religions, and to deny this is to be woefully ignorant of basic history. If all these various gods are aspects of one God, He must be crazy, cruel, or both, because His extremely inconsistent revelations and denigration of all His other religions have led to countless wars and lives lost over thousands of years.
The contradictory claims of different religions are less of a problem if truth is subjective.
You don't speak for all theists
Despite the feel-good message of tolerance and respect in this message, it is also very presumptuous. Walking into the average church, mosque, or (non-polytheistic) temple, and saying something like "All gods are the same God" would probably not get you a whole lot of supporters. You can't just say "you believe in a God that's the same as every other god" to most religious people without being rather rude, because it's intrinsically arrogant to tell other people what they believe.
Anyone who thinks that most religious people really would agree with a line like that needs to get some broader experience, because that's not how the world works right now.
Not all gods are the same
Even though people do believe in some sort of god, some people believe that animals and/or idols are god/s. This goes against the definition of what most religions define god to be.
What about Polytheism?
Polytheism, or the belief of multiple gods, contradict what most religions when they say that there's only one god.
Countering the tale of the Blind men and the Elephant
The tale used above could be a misleading false analogy for this reason: what the 3 blind men feel in the story is an Elephant existing in the physical realm, an element that can be easily proven to exist and with relatively understandable characteristics, a being other people with fully functioning eyesight can witness and analyze very clearly: Who are these beings with full knowledge about the elephant and its proprieties supposed to represent, if humans can only be the blind men according to the story? Is is very probable the theist will claim that the non-blind people are the theists of their own religion, but unless they can prove this is a fact and not just personal opinion (which is just as valid as a different theist saying it's their group seeing the true nature of a god), it isn't to be taken seriously. One could also compare the reality to this tale instead, where 3 blind men are trying to touch something in the air, one is saying "X (supernatural element supposedly existing in the air) is hard and smooth", another says "X is spiky and cold", and the 3rd "X is burning hot and fuzzy"; in other words, they attribute at times to the unfalsifiable entity mutually exclusive traits, completely contradicting each other. Each blind man could also claim that the others are actually touching Y, another hypothetical supernatural entity trying to deceive them. Nothing prevents them either from telling a person trying to "feel X in the air" unsuccessfully that this entity exists but changes its invisible form as to not be directly touched by some. Anyone with a grasp on reality and some common sense would see there's something wrong with the whole picture. Atheists or skeptics wouldn't necessarily be (in the story) people with good eyes who see the full and complete truth, but simply people demanding convincing evidence for this mysterious X everyone speaks of differently and its exact nature.
Perspective of the narrator
Apologists also point out the perspective of the narrator seems to imply an objective truth.
- "This may seem persuasive until you ask yourself one question: “What’s the perspective of the one telling the parable?” Hmmmm, let’s see, the one telling the parable. . . . He appears to have an objective perspective of the entire proceeding because he can see that the blind men are mistaken. Exactly! In fact, he wouldn’t know that the blind men were wrong unless he had an objective perspective of what was right! So if the person telling the parable can have an objective perspective, why can’t the blind men?"
This misses the point of the analogy in that truth might exist, but we (as the proverbial blind men) cannot directly perceive the elephant and are therefore limited in what truth we can attain. Just because person independent truth exists doesn't mean we have access to it!