Not inherently disagreeing with you at all. I'm not just sure whether we should look as far back as the 1600s. Yes some American colonies were founded by religious extremists.

But the divergence between US and Europe didn't happen until the late 1800s if not the early 1900s.

e.g. according to the census of 1851 ~40% of people in Britain were regularly attending religious services. No hard figures for the US from the time but from what I can find the proportion in the US was comparable. Except while mid 1800s was pretty much the peak in Britain in US it kept rising and reached its highest point in the 1950s while in UK religious participation had almost reached current levels by then.

IMHO the rise of political secularism, socialiam and the near societal collapse across much of Europe during and after WW1 and WW2 had a much bigger impact than whatever happened 400 years ago.