Being against Islam does not mean I should also be against Paganism.
Depends on how or why you're "against."
You could say I'm "against" Mormonism, because I am convinced it is based upon erroneous religious texts and teachings; nevertheless, I can honestly say I have never met a Mormon I didn't like; much in the everyday practice of the LDS faith is true, valuable and sincerely admirable; and Mormons are not an aggressive earthly threat to me in any way whatsoever.
I can't think of any Pagans offhand that are a threat, except for the ones I've met that staff abortion clinics (and they could just as well have been apostate Christians or secular Jews.)
Islam, however, is a explosive, bloody-handed, socio-political menace; not that there are not peaceable Muslims, but that their religious texts and their putative prophet (unlike, say, Christ or Gaia) explicitly incite religious violence.