Is it a mistake for Hamlet to trust in the Ghost?

Before discussing this topic, it’s important to realize the Roman Catholic teaching about ghosts that would have been prevalent in Hamlet’s time. During Hamlet’s time, the Roman Catholic Church taught that any kind of specter or ghost could be one of two things:
A soul that wasn’t quite able to make it to heaven due to past sin and is therefore unsettled enough to roam the earth with a mission until achieving the “State of Grace” possible for the Beatific Vision. This kind of soul, then, needs to be “purged” of former sins and is spending this strange time on earth as its Purgatory.
A demon that has no desire for the good of humanity and whose sole purpose is damning souls to hell. In regards to the first idea, Hamlet does admit at one point that this strange ghost might be in fact “a spirit of good health.” It isn’t long after that that Hamlet admits the ghost could also very well be “a goblin damn’d,” therefore admitting the second possibility.
To assume that Hamlet’s trust in the ghost is, in fact, his tragic flaw is to believe precisely in the second Roman Catholic teaching mentioned above: that the ghost is demonic and wants to damn Hamlet to hell. All of the examples above point to that theory. While most are self-explanatory, the fifth and sixth examples need some evidence attached. Hamlet has already revealed a few things to his friends and then asks them to “Never make known what you have seen tonight." All of Hamlet’s friends are in the middle of promising him not to tell when everyone hears the ghost chime in with the word “swear” three times. In regards to the last example, we must note the stage directions. When the ghost first asks Hamlet and all his friends to swear, the stage directions are non-existent: "Ghost. Swear." The next time, the stage directions become more specific: "Ghost. [Beneath] Swear." The final time, the stage directions damn the ghost as well as give more specific direction: "Ghost. [Beneath] Swear by his sword." It’s the word "[Beneath]" that should perplex the reader. Does Shakespeare mean that spirits are simply meant to be unseen? Or could this mean that instead of being from “above” in heaven, this ghost is really from “below” in hell?