I can't bring myself to 'believe' in Christianity. But I also don't 'believe' it is all made up. I have no faith for or against.
I absolutely 'believe' that the self described 'pagan religions' are 100% man made manufactured, largely in the late 1800s, final touches in the 1900, and drawing heavily on masonic mysticism, which was also manufactured by drawing from a number of popular sources.....
As far as 'truth' goes, the difference between scientology and modern paganism is that scientology was founded a little bit latter.
Although unlike scientology, I'm cool with pagans believing whatever floats their boat. A fair number are also completely responsible members of society with a belief system that reinforces that, which speaks VERY well of their religion.
Oh, and a note to any pagans: The Old Wicca burned witches (or killed them in other 'imaginative' ways). About the ONLY ancient faith that did NOT do that were early Christians. Later Christians did do it, because they never managed to purge the pre-Christian belief in witches from the population, and were eventually infected by it.
ALL societies that believed in human use of magic also believed in human abuse of magic.
ALL societies that believed in human abuse of magic had a word that translates to "Witch".
ALL such societies killed witches in 'special' (Horrible) ways. And many still do.
The ancient Celts were no exception. The ancient Wicca burned witches.