There's a fascinating lengthy essay here in the Dec 2017 issue of First Things entitled "Culture Is Downstream of Politics". While a call to action, the piece is particularly enlightening with its thesis that culture flows from politics and not the other way around. Focusing primarily on the examples of traditional marriage and abortion, the authors present a persuasive case that contrary to popular wisdom, culture indeed flows from politics.
Walk into any room full of Christian conservative donors, and someone will say, “Politics is downstream of culture.” Every head in the room will nod. Nothing is more entrenched as conventional wisdom among Christian conservatives. Like most truisms, this one is only partly true. As people change their beliefs about what is true and good, politics changes as well. But putting culture above politics as a distinct sphere is profoundly mistaken, for politics is part of culture.
Politics allows the American people to give public form to what they believe to be true, good, and important; it is also the main way Americans decide which views are “within the pale” and which are beyond it. Elites of the left dominate most other domains: the mainstream media, the academy, the arts, Hollywood, Madison Avenue, and increasingly the Chamber of Commerce and corporate suites. When an idea or issue drops out of politics, therefore, progressives can easily stigmatize it as outside the mainstream, extremist, and intolerable, effectively ending conversation. But election results feed back into culture .....
Politics is full of cultural content.
There is Scriptural support for the position that culture flows from political leadership.
The history of ancient Israel and Judah recorded in the Old Testament clearly indicates that evil political leadership was at the heart of the nation's slide into idolatry and debauchery. Remember that those political leaders were not elected but came into office through succession. As such, they were not a direct result of the desires of the population at the time. When wicked rulers were in power, the nation deteriorated. When a righteous leader (like Josiah) arose, the nation's descent into sin temporarily stopped and could even reverse itself. In other words, the culture flowed from the political leadership.
Political leaders who believe they are to reflect of the ethics of the populace are impotent and indecisive. Led by surveys, focus groups and polls, they are ships without a rudder. Weak leadership leads to indecisiveness within the culture. Evil leaders lead to cultural disintegration. Righteous leaders lead to cultural uplifting. It all starts at the top.