I hear a lot of controversy about the so-called 'prosperity gospel' (a term which those who believe that God prospers never use) but the same people never condemn usury.
The whole "prosperity gospel" thing is so vague, yet it always seems to carry the suspicion of wrongdoing, covetousness, pride, etc. Anyone who drops it should define it.
The Isaiah passage Jesus preached includes a message of financial prosperity to the poor. It doesn't mean you'll be filthy rich. Why would God you something that would send you to Hell? But He owns it all, and as His heir and a joint-heir with Jesus, so do you. Ponder that for a bit.
The character of God is impeccable and He wants the same for His children. So learning to be a yielded vessel is the first priority. At the same time, He wants to educate His children that they do own everything and provision is not an issue. It is absolutely necessary to get things done in this world. It must be believed first, and for that to happen, you have to have a preacher (and somebody who isn't afraid to bring up the subject).
It's good news and no one should be talked out of it, not for any implied wrongdoing, or any other reason. We're not called to look at others either and any mistakes they're making, or that we think they're making. You cannot see in the heart (on your own), and you'll be free'er not carrying the burden of suspicion about what others seemingly believe and adhere to.
The whole concept of usury is an interesting one. I don't believe it is intrinsically wrong to charge interest on a loan. That's how houses are bought. If your brother for personal reasons borrows money, I don't think interest should be charged.
On a professional thing in the world, the Jews were the ones who loaned money in the Middle Ages (because of the usury thing). It was looked down on back then. They were allowed to prosper doing this. When large debts were accrued at some points in history, they would be run out of town (loosing themselves from the debt at the same time).
Overall, people should just leave the "bad taste" part about how others see handle money. It keeps us from making unrighteous judgments about others and keeps your perspective pure. If' we're concerned about what the Lord wants from us (His plan in our lives), that should be well enough for us to be concerned over. It puts our flesh out of the way in the matter and leaves room for Him to actually give untainted wisdom about it.
We know what the fruits of wisdom are too. Just think of what Solomon had. The spirit of wisdom speaks too, to the simple ones and beckons us to reap similar rewards, but for the matters of the heart first, and the vision of prospering the kingdom (with money and our time and talents) as the highest priority.