A note about the writing in blood from episode 1x11 ("Red John's Friends"):

"He is mar" or "He is man". A man dying as he was would be pithy with his comment. If it were a name, he would have written the name, instead. No, he was writing something else:

"He is many."

At this point in the series we only knew of Red John as a serial killer. We did not know it was an entire cult. This message was a hint that this was planned from the beginning.

How else could Red John command the power and influence necessary to carry out his activities? The hint is reinforced by the episode title.

My theory is that Red John is a secret cult within Visualize. It may be that it is considered the highest echelon of Visualize, but more likely it is a splinter group within the organization that recruits from within. There is likely a charismaric leader, and that person is likely not Brett Stiles, and if not then Stiles would know who it is and fear him.