I seriously don't know what your problem is, Turtle.
Yes, historically most stuff was tied with religion in various perverse ways. Since you mention for example politics, remember that the Roman consuls during the _republic_ actually had religious duty and that being a Pontifex Maximus was a prescribed step in the Cursus Honorum. I.e., you _had_ to serve as a high priest before you could have any higher political appointment than that.
(Whereas nowadays, judging by some politicians, they dropped the priest part and you just have to be high

)
And then came the imperial cult, which reached ridiculous heights from Domitian onwards.
There just weren't that many atheists until _very_ recently. So there just wasn't much of a movement to separate everything from the church, except maybe when it got in the way of some king's own delusions of grandeur.
The Pilgrims that you mention, for example, weren't a bunch of cool secular dudes, but the nuttiest of the religious nuts in England. They were the ones who decided to leave the country and brave a new world just because they thought the Church Of England isn't fanatically protestant enough for them and they're not going to stay in a country where another sect is dominant. Even by Puritan standard, this was the radical millitant fringe.
Pretty much: why did you think they called themselves a religious name like "Pilgrims", anyway?
What makes you think these guys were so secular or so much in a hurry to separate church from marriage, or from anything else?