Sentence:  ... For, whenever his Bounty is miſus'd, by being made to miniſter to our Luſts or any unlawful Paſſions, if he ſhall ſtill ſuffer us to go on in an <WSD>uncheckt</WSD> Courſe of Proſperity, "That" is what may Pleaſe "Us", and "we" may be likely to think it God's Favour and Kindneſs to Us, which would really be one of his Greateſt Plagues. 
Meaning of the word marked with <WSD> tags:  Unrestrained, not held back.