Here's the first phrase (repeated as the third phrase):
The G# accidental provides a musical feeling of discomfort or error to accompany "temptation" in the line "Should some lust or sharp temptation" (first line of the second verse), "grieves" in "Ev'ry wound that pains or grieves me" (first line of the fourth verse), and "vices" in "With seductive, sinful vices" (third line of the third verse). It might even be something of a musical pun that G# is one of the notes to which "sharp temptation" is sung.
The seventh phrase also has a G# accidental, used to the same effect:
Here, the musical feeling of discomfort or error accompanies "sinning" in the line "Show the peril, and from sinning" (in the first verse), "wounded" in the line "Saying, 'Christ for me was wounded'" (second verse), and "temptation" in the line "And to master each temptation" (third verse).
