praying is not a problem. The biggest problem is lack of debt. Wanna open a new business? You can't take credit. Problems with cashflow? You can go to a debt prison. Forget about mortgage for a house etc.
It has consequence for enormous part of a life. For example, I was traveling using metro in Dubai. I had 5 dirham on my travel card and the trip I wanted to take costs 3 dirham. I couldn't enter the train, because the maximum charge is 8 dirham, so I could have negative balance.
GP is referring to the fact that interest is forbidden in Islam. However, you can still get interest-based loans in Muslim countries. They're just branded differently.
You can take out a mortgage in Saudi Arabia, Jordan, Bangladesh, Morocco.. They were the first four I checked.