According to The Independent, The Muslim Council of Britain has warned the players that wearing the shirts with this sponsor on it is against their religion so they aren't allowed to do it. Here's why:
Now I think that that vulnerable and needy exploitation part is bang on and although it's good financial business for Newcastle taking Wonga on, it's totally lame that they are now promoting a company that relies on people being in debt so that they can make more money out of them being in debt. I think they should go back to promoting 'Brown Ale' because that logo looked awesome on the shirt and the team with the best shirt always wins. If you have a bad shirt you never win anything. Let's review:"The idea is to protect the vulnerable and needy from exploitation by the rich and powerful."When they are lending and are charging large amounts of interest, it means the poor will have short-term benefit from the loan but long-term difficulty in paying it back.""The Islamic system is based on a non-interest-based system of transaction,"
This shirt looks cool and Newcastle finished 2nd. I have no other evidence.