People often wonder why it is that the Russian Missionaries in Alaska were able to evangelize the Indians there very quickly and convert entire tribes, and yet here in Protestant America, converts have only in the last few decades become numerous, and even still they mostly all come only after a good and long fight.
The reason is very simple. When the Aleuts heard the Orthodox Gospel from the Russian missionaries, they did not wrongly think that they already knew what these missionaries were talking about, and so they got it right the first time, and so never had to contend with heterodox misinterpretations of the Faith. Protestants, on the other hand, have in a sense been inoculated against the truth by having first been injected with a dead form of the Christian Faith. They thus have an immunity which is only over come with difficulty. A Protestant is almost never going to be able to accept Orthodoxy immediately upon his first exposure to it -- only after a long and painful period of dealing with the issues that separate them from Orthodoxy can they usually come to terms with it.