[Sir Francis Dashwood]

The Concise Columbia Encyclopedia says:
"Satan [Heb., = adversary], in Judaism, Christianity, and Islam,...

Paganism
Paganism, in the broadest sense includes all religions other than the true one revealed by God, and, in a narrower sense, all except Christianity, Judaism, and Mohammedanism.

Compare these two examples you give and you get:
Paganism = Satanism

Satan is a pagan entity, the "adversary" of Judaic theology.

[katnip]

Devil worshipping Satanism is a negation of Christianity.
It is an acknowledgement of the belief in the Christian God and the deliberate defilement of(adversary).
The word Pagan at it's origins means ignorant (of Christianity). I do not see how you can link the
ancient Celtic celebrations of the seasons with Satanism.