Every significant cultural, political or religious innovation has been fired up by them. In fact, every religion was founded by them. And, of course, America was as well.
Reformers who wanted to re-shape society by re-imagining what “We the People” could look like if we lived up to the ideals written on paper and signed in the blood of Revolutionaries.
Radicals who stirred up the masses and the minds of citizens to think beyond the old ways of doing things and thinking things. Radicals who fearlessly faced down the self-appointed “authorities” of Church and State, and faced up to the necessity of Change, Growth, Progress, Evolution … Humanity being better, indeed, more Human.
I just finished reading Holly Jackson’s excellent book, American Radicals: How Nineteenth-Century Protest Shaped the Nation. Jackson takes us into the lives and minds of women and men with wild ideas such as Equality, Freethought, Racial and Gender Justice, Communal societies and more. Fanny Wright, Frederick Douglass, Elizabeth Cady Stanton, Thoreau and many other lesser-known reforming radicals who shook their world, our world, with their risky and revolutionary protests and programs.
From the Introduction to American Radicals:
“Clearly, the country had a peculiar relationship to radicalism from the beginning.”
“Even as they aimed to ‘disorganize’ society at its roots, these radicals saw themselves as the true inheritors of the American project who would keep its ideals alive.”
From the Conclusion:
“These activists knew their aims were utopian and had every reason to expect defeat, but they tried for them anyway. All that they accomplished was fired by this mix of radical hope and unrelenting antagonism, their willingness to hazard failure rather than accept the world as they found it.”
And this Great Closing Line:
“Devoting their lives to a struggle with no end, they dared to begin.”
Who are they now? Where are they? Are we listening?
Friendly Freethinker 
Two who come immediately to mind are AOC and Dr. Barber,,, and I’d add Pope Francis : )
I have a hunch Holly Jackson’s discussion included Niebuhr — the lines you quote are making me think of him, especially in “The Irony of American History”: “Nothing that is worth doing can be achieved in our lifetime; therefore we must be saved by hope.”
I like how he continues — “Nothing which is true or beautiful or good makes complete sense in any immediate context of history; therefore we must be saved by faith. Nothing we do, however virtuous, can be accomplished alone; therefore, we are saved by love. No virtuous act is quite as virtuous from the standpoint of our friend or foe as it is from our standpoint. Therefore we must be saved by the final form of love, which is forgiveness.”
As a fellow Tar Heel (tho I was born one!), I HAVE to take that long view!! We were 27 years in Minnesota, and it was a heady experience to be suddenly voting in the majority!!! But being back here in 2008, and working with African Americans who I should have known growing up if it hadn’t been for segregation — was even more exhilarating and meaningful.
I’m reading A Promised Land, and love how Obama says “America” is an idea, not a location or a tribe.That’s exactly what I think: the idea of “liberty & justice for all” is not accomplished, but we hold on to and keep aiming at it!!! Because of this, any immigrant is totally as American as anyone else. — And — the goal surely seems more hopeful today than it did a few weeks ago. Truly Thanksgiving season!
Taking that long view and doing something constructive in the immediate, makes sense. The Idea of America seems a good way to approach this, I agree. Jackson’s focus is on the 19th C so I’ll have to find something similar for the 20th-21st! I often turn to Susan Jacoby’s “Freethinkers.”