Almost everybody in the world knows something about one of the major religions in the world aside from the one they practice, and it doesn't seem to have harmed them terribly much. What is it they are so worried about? It wouldn't have anything to do with the fact that it's a bunch of made up rubbish that has nothing to do with the realities of the things they claim to believe in, would it?
There are even people who call themselves Wiccans who have nothing to do with this larger body of people who follow these practices. They operate under the belief that anybody who wants to can worship the things they do without any special knowledge or approval. They don't have a hierarchy of priests and priestesses trying to impose their will on others or telling them the correct way in which to worship their deity.
The irony of all this is that the practice was intended for people in rural communities who were closely connected to the earth. These were people who didn't have calendars telling them when holidays were or anything like that. They lived according to the rhythms of the earth and the changing of the seasons. They knew when to plant and when to harvest (could they keep it in the ground an extra day or two to make it that much plumper or should they harvest it today because the first frost is fast approaching?) and had respect for the world they lived in.
If they ever thought to set themselves above this reality, they knew they would be tempting fate and risking disaster. Even when things didn't go that well (an early frost destroyed part of the crop or there were drought conditions for part of the season), they would still be grateful for what they did receive, knowing full well it could have been worse.
Like other religions that worship the natural world and preach working with nature rather than against her, it was born out of perceived necessity and an attempt to understand and explain the capriciousness of the natural world. If I want to have success in hunting food for my family, I will ask permission to kill something and will give an offering to the animal’s spirit in gratitude for providing its body to feed me.