No, it is a type of activity that is usually supplemental to, outside of, or transgressing against someone’s religion. On the one hand, “witch” and “witchcraft” are arbitrary labels that were given usually by people in an organized religion, to those who had different ways, on the other, it has relatively recently been reclaimed at least in some places.
In some belief systems, witches and witchcraft are a part of the established belief system, such as it is for the Yoruba. They are still shrouded in mystery though, and the ability to bridge the spirit and physical realm is considered a dangerous one. So witches are encouraged to use this ability for the benefit of their fellow adherents.
Wicca is a belief system that is built around the practice of western European, particularly UK area witchcraft. Wiccans do call themselves witches by virtue of adherence to their system whether or not they actively practice witchcraft aside of holidays.
Other witches though, can come from any belief system. There are even Christian, Muslim, and Jewish witches. Rather than being transgressive as they are often accused of being, usually by hypocrites, they are often more sincere in their religious practices than their peers. They must keep certain taboos and purifications and protections with earnest dedication because they are engaged in active spiritual practice. Hypocrisy or insincerity could be extremely dangerous for them.