“Looking back to the 30s, 40s, and 50s, black culture was pretty much indistinguishable from the rest of American culture.”
I have heard - but not seen verified - that during the period you mention church affiliations were higher and out of wedlock birth statistics were actually lower in the black population compared to the US population as a whole.
Then came The Great Society, War on Poverty, War on Drugs and Sexual Revolution.
Erik Bonhoeffer was the German minister who took his fight directly to the nazis (and eventually died for it). He found his particuliar brand of faith in black churches of America and took that back to Germany with him.
The left has since claimed him as they often do but Bonhoeffer sat in the pews long before liberation theology and social justice infected churches.
In his book “Bonhoeffer: Pastor, Martyr, Prophet, Spy” Eric Metaxas attempts to correct the record. Its a powerful story.