During the Golden Islamic era, good people were called as Muslims and evil people were called as non -Muslims

People who did not harm others were called as Muslims
people who achieved peace was called as Muslims
A man who did not divide people was called a Muslim

A man who had conscience within

Men who had conscience and conscientious towards his fellow beings were called as Muslims

As time passed, when people started to give importance to Arabic names, Arabic words, Arabic forms, Arabic expressions, fundamental religious guidelines, prophet’s Sunnah, worships, rituals, cultural habits, traditions and Hadiths, Dheenul Islam was confined to a community whose religion was decided by his/her birth, parents religion, pronouncement of a sentence (shahada) and following its fundamental guidelines

Conscientiousness and righteousness of a man was reduced (Became secondary) and more importance was given to the forms stated above in the name of prophet’s sunnah

Who was a Muslim and who was a None-Muslim was determined not by conscientiousness and righteousness religions but by his/her birth religion  not by Dheenul Islam (Dharmaya) which is called Spiritual Islam 

Later you and I were born at a time that this was accepted as norms