Why could not the pagan faith become the mainstay of the princely power?

Paganism was very motley. Different Slavic tribes worshiped different pagan gods. So in 980, the prince tried to carry out a pagan reform, where Pernu was supposed to become the head of the Slavic pantheon of gods, but, unfortunately, this reform failed. Many tribes refused to accept foreign gods. Thus, Vladimir had to go the other way. This other path turned out to be Christianity, which was introduced in 988.