Of course it's heresy.
This gospel of prosperity also motivated another writer, Max Weber to write an article about why Protestant countries are rich and why Catholic countries are poor.
This ideology fills the doctrine of the Evangelical sects that come south of the border to convert Latin Americans to their heresy. They do the same in Russia. They say our people's economic situation will prosper if we convert to Protestantism, they claim that the USA are wealthy because the pure gospel is followed there instead of the medieval traditions (refering to the Apostolic Churches).
An adaptation of this ideology is taught even by some Catholics. Criticisms against those who promote (some bishops like Onesimo Cepeda of Ecatepec and some RC orders like the Legionaries of Christ), state that during the cold war, they were fervently in favour of Liberation theology preaching Marxism (because of the support they had from the government and the ruling PRI) and that once the political environment changed they suddenly started promoting this gospel of prosperity.
I don't know if this opinion exists among the Orthodox. Probably it exists in the US because of so many former Protestants who join Orthodoxy.