Are anit-drug laws unconstitutional?

Yes they are in freedom of religion. There are people who use marijuana as a sacrament. In California there are churches that the members can go to and use marijuana. There are also Indigenous people who use Salvia in religion practice. However, if the members of your religion do not approve of it, then their is no constitutional right to use it and it's then just illegal. The Catholic church had been allowed to use alcoholic wines during the prohibition era