It's part of the "prosperity preaching" brand of Christianity very closely affiliated with the Word of Faith movement. Basically, they teach that God wants all Christians to be happy, financially prosperous, and free from disease and that Christians can claim victory over poverty or disease by "positive confession". This can take forms such as: quoting scriptures to Satan, telling him he has no power over you, and demanding he give in to your power as a child of God and free you from the disease (or poverty); demanding of God that he give you what he promised in his scriptures; or just affirming to yourself that, in the name of Jesus Christ, you are prosperous (or healed), even though in reality you are not. A typical teaching of theirs is that the bible is filled with promises of blessings God will give Christians but that you need to claim them and a lot of people are missing out by not claiming those blessings they are promised.

There's a lot more to it than I can get into here, but that's the gist of it; if you have encountered such theology before then you probably recognize what I am talking about now. There is a wealth of material out there that you can look into though. Both the entries for "Prosperity theology" and "Word of Faith" in wikipedia are pretty good, though somewhat biased.