Well, I think there's a few things that are for certain.  Obviously the William Blake theme is consistent throughout the show and the referencing can't just be a decoy.

A couple of facts:
1. We know that in the 7th episode of this season, we find out who red john is.
2. There are 7 suspects
3. The 7th episode is called "The Great Red Dragon"
4. "The Great Red Dragon" has 7 heads

A couple of thoughts:
1. Bruno Heller, with his love of theme and poetry & Blake, has purposely created the above situation.
2. Look up "The Great Red Dragon" on Wikipedia. The quote is right there for you all...

“And behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads. And his tail drew the third part of the stars of heaven, and did cast them to the earth.”

For me, and as a lot of other people have theorised, Red John is a 7-head collective of all of these men. I'm certain we'll find out specifics, but they're all involved and relevant. And all of them perform the different duties of Red John, and pose as him throughout the entire show. There may still be a 'master' Red John; but "the list is real" and all seven of them are a part of it.

All you people looking so ridiculously deep for tiny little fragments of coincidences are over-thinking it. I truly believe that Bruno Heller has left the series open for different endings and ideas. None of the hints are specific. He is Mar, thinking about the above was probably incomplete for "he is many".

Keep it simple.

Hi Mentalists,

I have some questions, please help me with your answers.

Question 1) 
When Partridge and RJ were in an abanadoned warehouse.....assuming that RJ called the cops using Partridge's cell phone, why did it get directed to lisbon? and not some other police patrol car in the area?) This only means that RJ knew lisbon was alone in her office and she would head for the warehouse......

Question 2) 
How come Lorelei had the list 2 months before RJ's office was raided by kirkland ?(assuming that the list was stolen during the raid).....and why is there no emphasis put on this point by CBI or Jane?

Question 3)
RJ went to see sophie miller and they both duscussed Jane's past  and his happy memories? Doesn't that seem a bit off for a professional like Sophie to discuss someone elses's life? and nowhere does she hint about this in her recording......

Question 4)
why doesn't jane ask rosalind harker to talk to the remaining 6 suspects to put an end to this drama? Jane would be the first person to do so......so this only means one thing.....that the list was deliberately planted by Jane to throw RJ off the track.....because as I see it, Jane is making no effort to get closer to the suspects on the list, instead he is tracking down people like sophie miller and such......

Question 5)
why did kirkland kill lennon in the hospital? what was his motive?

I don't know who is Red John but i have some clues i don't know how many of you have watched the movie Red Dragon with Hanibal Lector...The movie is based on serial killer character that is trancending and  becoming the seven headed beast from William Blake's painting The Great Red Dragon.In the Mentalist there is and episode called The Great Red Dragon and Red John always recited Tiger Tiger which is a William Blake's poem.Bonus round:The lover of the serial killer Red Dragon is blind and so is Red John's lover.

RJ is a ventriloquist. He speaks with his hands and suffers from coulrophobia.

Heller on Captain Kirk...

"Bob Kirkland (Kevin Corrigan): The Homeland Security agent is 'a dark horse,' according to Heller. 'If you were a betting man, he'd be an outside shot I think, but a good dark horse. He is probably the most mysterious of the candidates, and that makes him suspicious. His behavior sometimes, even what we've seen of his behavior, is inexplicable and even murderous. So, if he ain't Red John, he's certainly one weird cat.'"

Tiger's are kitty-cats, aren't they?

--------------------------------------------

Not so sure if this is a one man act...  

Kinda think Jane was had something to do with the air conditioning when his study was broken into...  Is he planning anything special?

Kirkland was talking to Tom on the phone...  But I'm just not seeing it as 'only' being the Sheriff--is that the point?  

Wonder if Red John is a ghost, his actions on the other hand (his right hand?), very real...  Stiles have anything to do with it?

If I had to go with one, it'd be Kirkland.  I like Partridge, (is he really dead?)  but Kirkland does fit the bill quite well--does he like Lisb'awn' as he first puts it?  He drinks Caesars like Jane does in the second last episode of season 5...  But what does that prove?

Meh, I'm enjoying the hunt!  If it's one person, I'll stick with Tiger's being cats...Captain Kirk all the way.
(Maybe Red John doesn't pull the trigger...  His Right Hand does...)

Love all your theories folks!

There is something I just realized, they said Simon did those (at least some) Red John voices right? Now please imagine the upcoming scene when finally Patrick meets Red John face to face, let's say for example that Red John is, I don't know, Gale Bertram who has a deep voice, very different from that Simon-Red-John-voice on the phone calls.
Now the thing is will they just dub a face-to-face scene? That would be really stupid and nonsense, so my point...I think none of us is considering the voice itself as a huge clue as it seems to me, all that clues like ''suspect X is left/right handed and so he is Red John" or "someone said something in X episode that means he is Red John" I think those theories are unlikely but not impossible.

Back to my point, I assume that the pitched voice is his real voice, why? Easy. Remember that episode when Patrick meets a little girl who send a message to him? When Teresa and the team arrive, Patrick reveals that he hypnotized the girl because everyone who can identify Red John ends up dead, but before that he asked the girl how he was. AND if I recall right, she says something about his voice like "funny voice" something like that...and also the season 2 finale when they're face to face (or face to mask) and Red John has that voice just like that season 6x01 during the phone call, so I think it IS a relevant clue, therefore there are only two of the seven suspects that fits that voice, I mean, that can reach that voice easily, Bob Kirkland and Brett Partridge.

The show itself shows Bob as the more likely real Red John during season 5 so, a lot of movies with investigation involved, a lot of times the most obvious suspect is actually the real one.
About Partridge, he isn't a obvious suspect at first, but after checking websites like this one, there are a lot of plausible theories including him and so, he might be our guy and also I think he's the most likely Red John of all suspects.

PS: I think every theory here if it has a good point it is plausible, even if you don't agree with, I mean a lot of theories here including Bertram or Haffner I don't agree with, however they are plausible in some way. My point, don't downvote a theory if you just don't agree with it.

"HE IS MAR" -- MAR on Wikipedia says:  

"Mar or Mor (as pronounced respectively in eastern and western dialects, from Syriac: Mār(y), written with a silent final yodh) is a title of respect in Syriac, literally meaning 'my lord'. It is given to allsaints and is also used before Christian name of bishops.[1]"

MEANING --- "HE IS MY LORD"

I think it's not meant to be a clue for us about a specific person, per se, as it wasn't written by a victim, and because MAR and MOR are used so widely throughout the show for various character names and places -- I think the MAR reference is about an overall theme and that "He IS Mar" was written by RJ or an RJ helper, and it is a message based on RJ's crazy, sadist thinking.  This statement must stand for something he believes in or considers himself to be -- which may be God, or the Devil, or in service of...

MAR & MOR also both can mean THE SEA and RED or to HARM.  Numerous references are made, including:

DuMAR Tanner, Lorelei MARtins, Ellis MARs, MARta & Virgil ROMan, MORgan Tolliver, Towlen MORgan, MARion Hicks, David MARtin, MARcia Wallace, Santa MARta, MARquesa, MAR Verde Real Estate Corp., RoseMARy Tennant, MARiska Kolpecki, Villa MARsante, MARsante Security --- and I'm sure many more... 

In the FIRST SEASON, there were some repeating themes: [besides MAR and MOR]:

1.  A REDHEADED CHARACTER appears in almost every episode, as well as names that mean RED

2.  The murders the CBI solve are generally about:  MONEY, SEX, REVENGE or ACCIDENTAL; but RED JOHN is entirely different.  His reasons are sicker and even more sinister, likely apart of some demented religiosity he's got going about himself.

3.  HYPNOSIS is featured and used by Jane, and mentioned often --- one episode centers around it, too -- a tool that is probably greatly utilized by RJ.

4.  CLOWNS:  PJ is called a clown in several episodes; and then there's the smiley face and carney background

5.  BOATS/MARINAS/the OCEAN/MOBY DICK THEMES -- a guy is caught when Jane spots a copy of MB, realizing he's a smart guy who is hiding behind a "slow" persona.

6.  TWINS or a CHILD that was kept secret

7.  GOLF:  FIRST episode was about golfers/Tagliaferro & Tolliver both mean "cut iron" or "iron cutters" --- which could also mean a golf club