Sentence:  This was that which made the old Christians <WSD>paganize</WSD>, while by their scandalous and base conforming to Heathenism they did no more, when they had done their utmost, but bring some Pagans to christianize; for true Christians they neither were themselves, nor could make other such in this fashion. 
Meaning of the word marked with <WSD> tags:  To behave like a pagan.