We’re talking about a very diffuse historical movement, or series of movements.
It’s difficult enough with something like conservatism. I’ve been a conservative my whole life and every so often I encounter a member of “the family” that makes me think–who are you, where are you from, and what could we possibly have in common? (This has happened a lot the last couple years.) I would need to narrow it down to get a sense of who my “immediate family” is. For myself politically, that might mean kinship with people who value individual rights (freedom of the press, freedom of association, freedom of religious practice, etc.), private property ownership, subsidiarity, the value of vibrant voluntary organizations, the rule of law rather than of charismatic personalities, the government refraining from playing favorites with industries or companies, public order, checks and balances, etc. You’ll notice that a number of those categories are going to infringe on each other, and it’s quite the mouthful…
I can’t help but notice that a lot of the newer sort of internet right people don’t seem very keen on a lot of those concepts.
“The thing with Plato and Aristotle however are that, I think it’s a good bet that if they had lived after the coming of Christ, they would have been devout Catholics like Aquinas.”
I grant that if they’d lived within the Christian era, they would have been Christians, but at the same time, I think that if they lived at the time of St. Paul, it’s quite likely that they would have died pagans. Even St. Augustine (died 430 AD) took his own sweet time converting to Christianity, and he’d had a Christian mother and had lived his whole life with Christianity being legal in the Roman Empire. Even his mother had been born after the legalization of Christianity.
I am not familiar with the biographies of all of the 19th/20th century characters you mention, but with regard to Margaret Sanger, this bit from Wikipedia sounds like it explains a lot:
“Anne Higgins [Sanger’s mother] went through 18 pregnancies (with 11 live births) in 22 years before dying at the age of 49. Sanger was the sixth of eleven surviving children, and spent much of her youth assisting with household chores and caring for her younger siblings.”