As I understand it, Cisse's stated objection on religious grounds is all to do with his faith's belief that certain elements of western banking systems (the idea of charging or receiving interest, particularly,) are wrong. Good for him, eh?
Well, some things to consider:
When Cisse signed, Newcastle's shirt sponsors were Northern Rock.
Last season, Newcastle's shirt sponsors were Virgin Money.
Both are interest-charging banking concerns.
For me, Cisse wants to leave Newcastle for more money somewhere else, and has used the general distaste for Wonga and their like to make a "principled stand" that he hopes will see him sold on, and that he had no concerns about when the interest rate of the firm on his shirt was only 52.1% apr variable (Virgin Black credit card, 2013.)