They know that the only way they can survive is to portray themselves victims of intolerance and bigotry and then qualify for special privileges granted by the state. Witchcraft is a problem today, because witches are gaining special rights status by claiming that they are a persecuted minority. The danger lies not in church or state persecuting witches. The real danger is when either oversteps its God-given authority, or when one tries to be the other. That is what leads to tyranny and oppression.
Witches certainly can hold their beliefs and practices in private.
There can be no civil law against that as long as it doesn't interfere with public sphere of life. Private faith is an issue of the conscience. The state of the human soul is something which only God himself can judge. From another perspective, the problem of witchcraft is rooted in the deep spiritual decline of our churches. Our response as the Church should be to pray for her salvation.