First of all, in my opinion, there is nothing rude about Rob's objection to the analogy. I think that we should respect people's right to hold a belief, but we do not need to respect the belief itself, especially when that person presents it to us in a debate forum.
I agree with Rob's criticism. I think the following analogy is more appropriate:
A traveler is wandering in a desert. He is terribly thirsty and fears that he might die of dehydration. Fortunately, just then he comes upon a beautiful oasis. He can see all sorts of people splashing in the water. He is rushes over and is about to enjoy the refreshing water when three people standing a ways from the oasis call to him, "Stop! To enter the water is death."
Naturally, the man slams on the brakes. He approaches the three, noticing their dehydrated appearance, and asks, "Did I hear you correctly? How is it death? Look at all the people playing and splashing."
"There are alligators in that water," the three reply, "Someday the alligators will eat these people."
"If you want to live, leave the water and go over there," says one of the three, pointing off away from the oasis. The man looks and sees a large crowd of people. They are splashing and drinking and laughing, but not in water. It seems that they are splashing and drinking sand! Looking closer, the man notices still bodies and skeletons interspersed among the crowd. Even as he takes in the bewildering spectacle, he sees a member of the crowd, who appears to be laughing deliriously, fall to the ground motionless.
"They are drinking sand!" the traveler exclaims.
"Yes, but that sand quenches your thirst more than all the bitter water in this oasis. Besides, remember that there are alligators in here. There are none there. Just remember: to taste the quenching sand, all you must do is believe that the sand is quenching your thirst. Even when it feels like it is killing you, believe, and your thirst will be quenched."
The traveler is a confused, but before he can question further, another of three speaks up. "You are right, traveler. That place is nothing but ordinary sand. My companion is correct that this oasis is death, but the true quenching sand is over that way." The speaker points off in another direction.
Looking that way, the traveler sees a similar display as before. Though the sand looks a little different there, he still notices skeletons and corpses scattered among the crowd.
Before the traveler can question, the third person speaks. "Both of my companions have told you a falsehood. While this oasis is death, the real quenching sand is over there." The speaker points, and once again the traveler sees a similar display.
Immediately the other two speakers protest, and within moments, the three are engaged in a violent argument about which area contains the quenching sand. Quietly, the traveler slips away and enters the oasis.
Enjoying the life-giving water, the traveler turns to a fellow beside him. "Those three told me that this water was death."
"I know," the man replies, "They tell everyone that. Occasionally, one of them dies of thirst, but they are always replaced by some one else. The new one will say the same thing, but point to a different area. Lay aside your fears. I have been here for years and have not witnessed any signs of an alligator."
"How can you be absolutely certain that there is no quenching sand?" asks the traveler.
"I'm not," replies the man with a smile, "but isn't the water lovely?"
[edited multiple times to correct small grammatical errors]