Calling it a religion. Religion requires the individual to conform to the theology and doctrine of whatever religion it is. Religion requires the individual to be totally obedient to the priesthood of that religion. Wicca, or whatever name you choose, is a path for those seeking the hidden spiritual knowledge made secret by the imposition of religious theology. Religion would declare heretic and burn at the stake all those who don't conform to its imposed theology. Wicca, withcraft does not.
The path of seeking spiritual knowledge is open to all and all follow their own individual path even if they join a group. All of this is illustrated in the occult symbol of the labyrinth.