I posted this further up but John Ingersoll was the most famous atheist of the day and a friend of Brown and said this

But the real pioneer in America was old John Brown. Moved not by prejudice, not by love of his blood, or his color, but by an infinite love of Liberty, of Right, of justice, almost single- handed, he attacked the monster, with thirty million people against him. His head was wrong. He miscalculated his forces; but his heart was right. He struck the sublimest blow of the age for freedom. It was said of him that he stepped from the gallows to the throne of God. It was said that he had made the scaffold to Liberty what Christ had made the cross to Christianity.