Manifest Destiny was less of a well-thought-out strategy and more of a rallying cry or a core conviction. Even though many US officials viewed it as immoral or antithetical to what the US stood for, it permeated the leadership's beliefs for decades. (In other words, even the most "liberal" minded people harbored the notion of white, Christian, American dominance, despite the fact that many others detested it or thought the name was inappropriate.) Both an embodiment of that notion and a planned political ploy, the Louisiana Purchase was opposed by many Americans. Nevertheless, Thomas Jefferson did support the notion of gentile white landowners "lifting up" the unruly, wild continent and creating an agrarian society. He saw "gentleman farming" as one of the most honorable occupations, and he used it to buy land for American immigrants as well as to keep Louisiana out of the hands of the British or Spanish (albeit interestingly, it was purchased through a British bank). What does that imply about the objective? It implies that Manifest Destiny's objective wasn't truly something that was fixed in stone. Before the Louisiana Purchase, John Adams saw a US that crossed continents. Some imperialists imagined a scenario in which the United States controlled all of the Americas or just North America. It merely implies that the US was mostly hypocritical (as nations have a tendency to be) in pursuing a goal at the expense of individuals it trampled on, depending on the lofty aspirations of the person. (I say this as an American who is pleased with how history turned out but who is also aware of people who were injured by it.)
The First Amendment's Establishment Clause prohibits the government from making any law “respecting an establishment of religion.” This clause not only forbids the government from establishing an official religion, but also prohibits government actions that unduly favor one religion over another.
