Are we playing as the main character from FC2???....
Heres my thinking..
On the box art of FC5, theres a guy tied up on the bottom right, with sinner carved in his back.
He is white and has a short brown haircut.
Just like the main character you play as in FC2!
Id be willing to bet, that 'sinner' wronged the cult, and broke his way out, similar in some fashion to FC3.
I bet he is the character from FC2, who returned back to the states, maybe with his riches, and guns, and became, or originally set up this group, which maybe was taken over by the religious guy.
THeres gotta be a tie in...Ubi knows we love FC2, how badass would it be to make a nod to that by playing him again?