"actually believe that they were doing God service in persecuting His people, yet their sincerity did not render them guiltless. The light that would have saved them from deception, from staining their souls with bloodguiltiness, they had willfully rejected. GC 229.1"
"They shall put you out of the synagogues: yea, the time cometh, that whosoever killeth you will think that he doeth God service."
The EGW passage directly echoes the sentiment expressed in John 16:2, where people persecuting others believe they are serving God. The phrase 'doing God service' is a clear indicator of a direct connection.