Sentence:  ... beside the deceitfulness of the heart and the carnality common to all men, the deep ignorance of the heathen, the abjectness of their social condition, their vain but venerated traditions, their time-honored customs of profligacy, impelling to infanticide, parricide, <WSD>Thuggish</WSD> murders, and cannibalism—all conflict steadily with the holiest efforts to transform them into symmetrical Christians. 
Meaning of the word marked with <WSD> tags:  Resembling (the behaviour of) the assassins known as thugs or Thuggees (often capitalized in this sense).