Carrollton, Ga. — Jon Ossoff’s defeat in Georgia’s Sixth Congressional District election on Tuesday wasn’t just a sign that Democrats may have a harder time winning in the Trump era than they had hoped. It is a symptom of a larger problem for the party — a generational and racial divide between a largely secular group of young, white party activists and an older electorate that is more religious and more socially conservative.

Put simply, outside of a few progressive districts, secular-minded young activists in the party are unable to win voters’ trust.

Mr. Ossoff, 30, represented this new wing of the party. He said almost nothing about his religious beliefs or the way in which his Jewish upbringing affected his political views — probably because, like many white, college-educated Democratic activists of his generation, religion didn’t shape his political beliefs.

Mr. Ossoff’s secularism would have surprised many American liberals of the 1950s and 1960s, who looked to the moral inspiration of the Rev. Dr. Martin Luther King Jr. and the theologian Reinhold Niebuhr, both of whom saw a religious imperative for social justice. The civil rights movement was grounded so thoroughly in the theology and culture of the African-American church that the historian David L. Chappell has called it a “religious revival.” And the economic views of New Deal and Great Society liberalism echoed the positions of mainline Protestant denominations and the social teachings of 20th-century Catholicism.