Complex sentence: As a newspaper editor, he became notorious for his relentless personal attacks against his religious and political opponents, sometimes to the point of being physically assaulted, while at the same time building a large base of fiercely loyal subscribers.
Split into simpler sentences: As a newspaper editor, he was notorious for his relentless personal attacks against his religious and political opponents, sometimes to the point of being physically assaulted. At the same time he was building a large base of fiercely loyal subscribers.