Consistency in Belief

The Holy Quran says : “And hold fast by the rope of Allah all together and be not disunited”. 3:103

Islamic teaching is the same for all people at all times. In that case, why is it that the same Muslim group in different countries or at different times profess different beliefs? Surely the belief does not change with the country one lives in! Here examples are given to show how varying beliefs to suit brings Islam into disrepute.