I don't think you can paint Christianity with such a large stroke. There are about as many different varieties of Christianity as there are fish in the sea, and while I don't agree with their beliefs, there are some brands of Christianity that do not promote self-loathing.
However, most religions fit what you describe and promote the idea that you must always strive to be better, and instill a sense that you are never good enough. The JWs are champ at it. It's a hard feeling to shake, especially when it is instilled from birth.