To say treating depression with medication is wrong is like saying treating people for colds, illnesses, and disease would be wrong as well.
I hate to see medicine used as a crutch, but it CAN Be a good thing. It isn't that you are a bad christian, it isn't that you don't have enough faith, it is that you ARE still human with a human body that was born imperfect.
Don't listen to those religious whackos.
When used properly, medication is a good thing. (Though some of the medicines used don't really help people anyway...butl, that's an entirely different topic for an entirely different thread.)