They don't believe everyone is shit. Their goal was to re-establish a centralized government over the wasteland. Autumn wanted Project Purity so that the people of the Wasteland would see the Enclave as saviors and protectors, and become their loyal citizens. Eden secretly wanted to use Project Purity to kill off any mutations. When Autumn wouldn't go along with that plan, Eden tries to recruit the player to do it behind everyone's back. Colonel Autumn's motives: "When you see the Enclave, you see the United States government. We are authorized to restore order and civility, by any means necessary." "You're in a heap of trouble, kid. You're a traitor to the United States government." "The American people are worth fighting for. The future must be secured." "Once this facility is operational, the masses will flock to the Enclave for fresh water, protection, and a plan for the future." "Once you're dead, we'll finish off this pathetic Brotherhood and become the true saviors of the Wasteland." President Eden's motives: "The United States was great once, and it can be again. There are plans in motion to see that this happens within your lifetime." "We cannot move forward until humanity can gain a solid foothold in the world. To do so, we must rid ourselves of the mutations that have plagued us for so long. These "Super Mutants", Ghouls, hideous creatures..." "Please recognize that the fate of our entire country rests on this plan. Sacrifices must be made for the greater good." "Once we have re-established ourselves, and brought civilization to the lands around us, then we can return to the old world policies." Relations between Eden and Autumn: "The good Colonel and I disagree on how best to approach the problem of the Wasteland. He feels my methods are too extreme. He has allowed his humanity to cloud his objectivity." Why the Enclave and Brotherhood can't get along - It boils down to two factions in Power Armor that don't like each other. The Enclave would probably want the Brotherhood of Steel to disarm and surrender themselves and all their tech, and the Brotherhood isn't going to do that. Each faction also believes that the Wasteland would be better off if they were the ones controlling Project Purity, even though the the rightful owners are the scientists that built it. Enclave's POV: "The so-called "Brotherhood of Steel." Don't be fooled by their pseudo-knightly nonsense or supposed connections to the United States Army. These power-armored boy scouts are nothing more than common criminals with access to some antiquated technology. Criminals who have had the audacity to claim this country's most important military installation, the Pentagon, as their own personal clubhouse!" "The Brotherhood of Steel, in their arrogance, has claimed Project Purity as their own! They would steal the Enclave's work, steal America's water! It is only a matter of time before the traitors march on the purifier, and attempt to take it by force." Brotherhood of Steel's POV: "[The Enclave is] the greatest threat the Capital Wasteland has ever faced. The Brotherhood of Steel has encountered the Enclave before, you see. Over thirty years ago, back in California. They seek to control and destroy, all in the guise of restoring order." "I cannot -- I will not -- allow the Enclave to control the one thing that could bring even the slightest spark of hope to these people." "I had my reservations about engaging the Enclave. Their assault on the purifier forced our hand. We had no choice but to engage them directly."