Response: "If one were to take a naturalistic view point on religion, how would religion originate?" - Kim

I think both of the ways you suggested could be possibilities if one were to take a naturalistic view. When you look at more ancient religions, you can see where influence has come into play. The Romans were are a great example of this. They took primarily the Hellenistic view that the Greeks had, and organized a central structure around that. However, they always maintained an open mind when finding a new religion, making the Gods of people that they conquered their Gods as well. This is summed up well in both how their influence can be seen in countries today that were once under Roman occupation, as well as how the Empire itself became Christian. The willingness of the population to convert must have been a tumultuous and controversial time, but it stuck, eventually developing the Roman Catholic Church, one of the strongest powers in Christian history. Delving even further into Christianity, we see how closely Jesus represents Horus: Virgin birth, son of God, mother (Isis-Meri vs. Mary/Miriam), father (Jo-Seph vs. Joseph), born of royal descent, both have their births announced by angels, both have assassination attempts (Herut vs. Herod), both are Shepards, both are 30 when they are baptized by a baptizer in a river just before the baptizer is beheaded. Now, with all these similarities in their stories (and more), it can be argued that the authors of the Bible, whether they knew Jesus as a person or as the actual son of God, attributed the mythologies associated with Horus, who was "the Jesus" of a powerful religion not far from their homeland, to Jesus himself. Whether or not any of this is true because of that is up for debate (or maybe mankind's saviors just happen to live similar lifestyles).
On the other side, we can also find examples of religions that seem to spring up over night from a single author. Scientology is a good recent case of this. The founder of Scientology, L. Ron Hubbard, wrote the works that detail the entirety of the religion in its original form. He also spent the majority of his life as a science fiction writer, but the common follower of Scientology will overlook this fact, chalking it up to him finding some kind of real truth and using his already established writing ability to communicate what he had learned about the universe. This is a religion originating from one man, over a brief period of time, whose followers take the whole matter very seriously and are elevated to the same legal status as any other religion. This pertains to your example of one person seeing benefits in drawing others to his cause and so making up the entirety of the religion himself.
So I would maintain, given a naturalistic standpoint (which I find myself to be in), both of your suggestions as to the origins of religions can be valid. I would go further to say that there are even more ways that a religion can be created, and if you find a religion that started in such a manner, you can find another that works along the same lines.

Should a religion created seemingly overnight by one man be accredited with the same status as a religion that has existed for hundreds or thousands of years and has millions of followers?
(ex.: Scientology vs. Christianity / Islam)