It is not really possible to know for sure what factor was most important in making Europeans want to colonize North America. Historians generally say that there were three main important factors, but it is impossible to know which factor was most important. These three factors are summarized as “God, gold, and glory.” Of these, I would argue that “gold” was the most important factor in motivating most Europeans and most European countries to explore.
This is not to say that “God” and “glory” were not important. It is likely that many Europeans really thought that it was important to bring Christianity to the people of the New World. It is also likely that some people wanted to have the glory of being the first to find a given new place. Even so, it seems much more likely that these people would have been motivated most strongly by tangible, economic benefits.
Countries would have wanted to send explorers out to find sources of revenue. This would help them to have more power in the world. Explorers would have wanted to get the kind of riches that they might obtain by finding a new area of the world that might have gold or silver deposits. This seems to be a much more likely motivation than less tangible things like God and glory.