Why do we need to suppose there is only one way to live or to view the world? On the other hand, if we all suddenly became convinced that there is one set of objective truths, accepting that fact...

Why do we need to suppose there is only one way to live or to view the world? On the other hand, if we all suddenly became convinced that there is one set of objective truths, accepting that fact alone would not cause us to change most of the beliefs that we currently have. Each of us would be convinced that the beliefs we held were the best account of the one true story of the world. So, in practical terms, what difference does objectivism make?