If my therapist truly believed in homeopathy (i.e. that diluting something makes it stronger) as something more than harnessing the placebo effect, I'd question his judgment.

If he didn't believe in it but was peddling it to people, I'd question his ethics.

Either way, I'd have a really hard time continuing to see a therapist who practiced homeopathy, but if they were otherwise a really good therapist, I'd probably talk to him about it before quitting.