Community, Identity, and Stability are engineered by the state through a top-down dictatorship with Mustapha Mond at its current head. As he explains, after the Nine Years' War, people so craved stability that they were more than willing to give up their freedom in exchange.
Identity is therefore preplanned. People no long procreate the natural way: sex is completely divorced from having children. Babies are produced through fertilizing eggs in a laboratory, and, especially in the lower castes, producing large batches of identical twins. Your intelligence, looks, and place in society are determined before you are born, and there is no possibility of changing your caste. You are then conditioned, through repeated tapes played at night and through activities during the day, to be happy with and adjusted to your assigned caste.
Community is achieved through conditioning. Further, the family has been abolished in favor of ties to the larger community. People are taught that it is healthy to have shallow relationships and many sex partners, an idea reinforced by the orgies that have replaced religion. People are taught that they all belong to each other. Being alone is frowned upon as abnormal.
Stability is achieved through dictatorship, soma, and consumption. If, for some reason, you are not feeling happy, you simply pop a pill (soma) and all is well as you move into drugged bliss. The government also understands it must have full employment to remain stable, and so it encourages people to buy, buy, buy, and insists that sports be complicated, with much equipment. This keeps the factories going strong and people in jobs.
People are not encouraged to think, and the arts, real science, real religion, deep relationships, sacrificing for another, and soul-growing suffering have been abandoned for a stable life in a perpetual Happy Land.