Ballou, son of a New Hampshire farmer-preacher, was raised in a Calvinist Baptist home. Unable to reconcile belief in a loving, all-powerful God with the idea of eternal punishment for most of humanity, he searched the Bible diligently and thought his way to a belief in universal salvation. By 1791, at the age of nineteen, he was preaching Universalist sermons. Three years later Ballou was ordained, and for the next fifteen years was an itinerant and circuit-riding minister, mostly in Vermont. During this period he prepared and published his book.
In his Treatise, Ballou focused on what he considered orthodoxy's weakest point: the doctrine of substitutionary atonement, the idea that Jesus' death paid for human sin. His treatment was deterministic, acknowledging God to be all-knowing and all-powerful. It was also rationalistic, drawing heavily on Deist thought, and rejected the doctrine of the Trinity—making Ballou a unitarian Universalist.
A Treatise on Atonement can perhaps be best understood by comparing its major points with those of orthodox Calvinist Christianity:
Orthodoxy considered sin to be infinite evil, total defiance of God's will. Ballou, on the other hand, regarded sin as finite, and therefore far less serious—"the violation of a law which exists in the mind, which law is the imperfect knowledge men have of moral good." The most that human beings can do is come to the best understanding of moral good that is possible for them and act accordingly. To sin is to do otherwise.
Orthodoxy considered humanity's punishment for its infinite sin as separation from an angry God. Ballou, by contrast, saw men and women struggling to turn toward moral good and away from the sins that separated them from a loving God. Orthodoxy required Christ to take on the burden of humanity's sin by being sacrificed on the cross, thereby atoning for sin and making it possible for an appeased God to be reconciled with humanity. Ballou, on the other hand, contended that Christ's death released a great spirit of love into the world, making men and women who were receptive to this spirit better able to atone for their own sins and be reconciled with God.
Thus Ballou argued that the orthodox had things backward: It was humanity that needed to be reconciled to God, not God to humanity. Moreover, this atoning spirit of love was available not only to Christians, but to all people, irrespective of "names, sects, denominations, people, or kingdoms." In no case would anyone be sent to eternal punishment by a loving God. No sin was that great; salvation was universal.
The Treatise made a strong and immediate impact, giving Universalists a common theological base from which to spread their message. Ballou was quickly recognized as the leader of the Universalist movement. In 1809 he left his circuit to accept a call to a settled ministry in Portsmouth, New Hampshire, followed by ministries in Salem and Boston.
In 1845, after preaching his hopeful, liberating message for more than fifty years, the aging Ballou relinquished day-to-day leadership of his Boston church. He lived on for another six years, deeply honored and respected as "Father Ballou," the "elder statesman" of Universalism. When he died, there were many tributes, none more apt than that of the great Unitarian preacher, Theodore Parker:
"He went through the land proclaiming this great truth, and he has wrought a revolution in the thoughts and minds of men more mighty than any which has been accomplished during the same time by all the politicians of the nation."