Sentence:  A century ago , Newman saw that liberalism ( what we now might call secularism ) would gradually but definitely make its mark on English Protestantism , and that even high Anglicanism would someday no longer be a `` serviceable breakwater against <WSD>doctrinal</WSD> errors more fundamental than its own '' . 
Meaning of the word marked with <WSD> tags:  relating to or involving or preoccupied with doctrine