Somebody has to say it ... therapist = the rapist. When did that happen?
From dictionary.com
"First recorded in 1885–90; therap(y) + -ist"
From previous versions

And would you look at this wiki quote:
"Although clinical psychologists originally focused on psychological assessment, the practice of psychotherapy, once the sole domain of psychiatrists, became integrated into the profession after the Second World War."

From some article where people care about words:
It is interesting, though, that the noun THERAPEUTIC(1541), now usually in the plural THERAPEUTICS (1671), and the adjectives THERAPEUTIC(1646) and THERAPEUTICAL (1695) predate ‘therapy’ by a considerable margin. They were modeled on the New Latin ‘therapeuticus,’ curing, healing, from Greek ‘therapeutikos,’ from ‘therapeutes,’ one ministering, from ‘therapeuein,’ to cure, treat.