Were most of the initial founders of the North American colonies really dissident Christians fleeing religious persecution in Europe? I've heard it said a number of times, but I wondered if it is actually the case.
Depends on the colony -
Generically, historians have posited there are two influences in American development - God and Mammon. God is a more northerly thing, and the explanation goes that is the reason the Northeast tends to be more "socialistic" or paternal in its governance. By contrast, the South was a more money-based thing, in which laisez-faire economics would be more valued - hence Texas' reputation as the reddest of the red states, and Massachusetts' as a blustery blue*.
Finally, the Spanish influence ostensibly mixed both Religion and Money - but in no event was it the persecuted fleeing Europe. Rather, it was the establishment church in much of the West and in Florida that at least came along for the ride.
So, short answer - depends on where you're talking.
And now for the obligatory hand-grenade: (Meaning, I'm being a bit tounge-in-cheek here)
*Personally, I've always thought these colors were backwards, as I used to think of Massachusetts as a pinko-communist sort of place....
I don't think any serious, honest historian would deny that people seeking religious freedom were an important component of the early settlers. Whether they were "most" is probably unanswerable. I don't think anyone took a survey at the time asking, "Are you coming here for religious reasons?" so they could then carefully tabulate 52% yes, 48% no or whatever. Even if someone had, many settlers likely had multiple reasons.
For example, Christopher Columbus said he was going to America to bring the Gospel to the Indians, and also to find a better trade route to the Indies. He negotiated with the king for a percentage of any money made from trade routes he established, and he worked to bring missionaries. (I'm not saying that Columbus was a dissident, he's just a prominent example of someone with multiple motives.)
There's nothing odd about this. Suppose someone asked you why you took you present job. You likely have many reasons: salary, benefits, working conditions, interesting work, opportunities for advancement, convenient commute, etc etc.
Also, you specifically say "dissidents". Many early settlers were comitted Christians, but not particularly dissidents. Many settlers of South America in particular were committed Catholics, at a time when their government fully supported Catholicism.