Sentence:  If my supposition be true, then the consequence which I have assumed in my Poem may be also true; namely, that <WSD>Deism</WSD>, or the principles of natural worship, are only the faint remnants or dying flames of reveal'd religion in the posterity of Noah. 
Meaning of the word marked with <WSD> tags:  A philosophical belief in the existence of a god (or goddess) knowable through human reason; especially, a belief in a creator god unaccompanied by any belief in supernatural phenomena or specific religious doctrines.