What does O'Sullivan mean when he says that Manifest Destiny was given to America by “Providence” (by God) to continue the great experiment of Liberty & Democracy?

O'Sullivan means that he believes Manifest Destiny, the idea that the United States was destined to expand and spread democracy and freedom across the continent, was a divine mandate from God. He sees the expansion of American territory as part of a larger plan by a higher power to promote liberty and democracy in the world. By invoking the concept of "Providence," O'Sullivan is suggesting that America's destiny to spread liberty and democracy is ordained and guided by God.