How did O'Sullivan make the drive to expand sound like a noble goal?

John O'Sullivan, a newspaper writer from the New York Post, was once quoted as saying that "It is our (meaning the United States) manifest destiny to overspread and to possess the whole of the continent which Providence has given us." In this case, Sullivan feels that expanding America's influence and taking over territories from other groups of people/countries is something that is bound to happen. He uses religious grounds to support his view and considers the US taking over new territories as a foregone conclusion.