"British" and "American" are not accurate as stand-ins for Commonwealth and North American English more broadly; actual practice varies even among national publishers. The Australian government's Style Manual for Authors, Editors and Printers preserves the points in the abbreviations, but eschews the comma after them (it similarly drops the title's serial comma before "and", which most UK and many US publishers would retain).  Editing Canadian English by the Editors' Association of Canada uses the periods and the comma;  so does A Canadian Writer's Reference .  The government publication The Canadian Style uses the periods but not the comma. 
Rome, however, was more than just a warrior state. At home Romans believed in the importance of the family and the value of religion . They also believed that citizenship or civitas defined what it meant to be truly civilized. This concept of citizenship would soon be put to the test when the Roman territories began to challenge Roman authority. However, this constant state of war had not only made the Republic wealthy but it also helped mold its society. After the Macedonian Wars, the influence of the Greeks affected both Roman culture and religion. Under this Greek influence, the traditional Roman gods transformed. In Rome an individual’s personal expression of belief was unimportant, only a strict adherence to a rigid set of rituals, avoiding the dangers of religious fervor. Temples honoring these gods would be built throughout the empire.