Up to the early 1900s, the Protestant elite followed the older ideas about dominant Anglo-Saxon ethnicity. For instance, Kaufmann relates that although Josiah Strong in 1885 thought that,
no race should literally displace the other, he also spoke eloquently of the providential destiny of the Anglo-Saxon race to Christianize and Anglo-Saxonize the world.
According to Lyman Abbott,
it is the function of the Anglo-Saxon race to confer these gifts of civilization, through law, commerce and education...
Whatever we think of such beliefs, it is clearly the case that the idea was for people to assimilate to a dominant Anglo-Saxonism.
This changed between 1905 and 1913. The Protestant churches became more ecumenical in their outlook, based on an ethical universalism. In 1908, this ecumenical movement led to the creation of the Federal Council of Churches (FCC), an organisation involving 32 Protestant denominations. The period was to see the emergence of an interfaith movement, a Goodwill movement, support for internationalism, and for a pluralist concept of the nation in which no single group was dominant. Those who took this new line agitated for open borders.
There was also a spirit of "humanitarianism," based not so much on a rejection of God but on the idea that we should serve humanity rather than particular nations. Summarising the views of Everett Clinchy (1934), Kaufmann writes,
...America could call upon a liberal tradition. Drawing on this tradition, its proper mission should be to lead the world toward a higher stage of liberal evolution, culminating in a cosmopolitan world view.
Another ecumenical commentator wrote in 1936:
There can be no fully civilized world until the arrogant independence of political sovereignty can be subordinated to the welfare of human life as a whole. We are far from that now, but everywhere the most civilized minds are thinking in the new patterns of world relationships.
It's a humanitarianism that overrides and endangers particular identities and attachments.
It is important to note, though, that the FCC represented most of all a Protestant bureaucratic, establishment elite view, rather than a rank and file outlook. Its point of view was not generally accepted by rural clergymen, nor by the laity in general. Furthermore, prior to World War II its efforts to bring about open borders were successfully opposed by patriotic groups. For instance, here is Kaufmann on the passage of immigration restriction laws in 1924:
The Protestant establishment also vehemently opposed the National Origins Quota immigration act of 1924, which was subsequently passed. The opposition of the Protestant establishment to the new law was so extensive, and pervaded all of the denominations so completely, that Robert Moats Miller exclaimed: "A list of the men who publicly opposed the exclusion measure would read like an honor roll of American Protestantism. Much the same could be said of the religious press."
In 1942, an FCC conference,
advocated an American foreign policy that would end "the sovereign power of the nation state" and lay the basis for a world political order.
In the early 1950s the FCC (now the NCC) once again lobbied for non-discriminatory mass immigration.
So, the basic conclusion is that one of the roots of the movement toward open borders and multiculturalism was the Protestant establishment from about 1905 onwards. This means that it cannot just be cultural Marxism which is to blame for the current direction of American society. It was not just foreign intellectuals from the 1920s onwards, but changes within the Protestant elite from the very early 1900s, which helped to establish the current template.