read the article here: http://catholiceducation.org/articles/facts/fm0116.htm
To be brief, Fr. Longenecker answers 'yes' to the question. He doesn't think witches have green skin and pointed hats, and I guess he doesn't believe they fly around on brooms either. But he does think demonic possession is possible.
"Is it possible for modern people to summon up the ancient gods and goddesses and offer themselves to be infested by such spirits? Of course it is."
Among the other curious things he writes, Fr. Longenecker suggests that witches and other pagans, due to their 'evil' religions, were often possessed by demons. Thus, their conversion to Christ required long periods of catechesis and multiple exorcisms. I guess Fr. Longenecker is, for some reason, ignoring the biblical passage that says "Thou Shalt Not Suffer a Witch to Live" (Exodus 22:18)
This sort of selective scriptural memory is something that bothers me about Christianity, as about most organized religion. Here, Fr. Longenecker suggests prayer and fasting as a way to help those who are 'possessed'. He offers no objective reason for why he thinks demons exist, or why these neo-Pagans and others are possessed by evil. All he can offer is a long tradition of mistrust built on the scriptures and prejudices of the ancient Jews and Christians.
More important, why doesn't he mention the passage from Exodus? It is a famous passage. It has been used to justify the burning of witches throughout history. Why doesn't he mention it? I don't know. I doubt that he's unaware of it. Perhaps he didn't want to complicate the matter.
I'm reminded again of the relativity of human judgments. The priests and Christian laymen think witchcraft and ritual evil, while their own rituals are spotless and holy. Witches and other Pagans think the dogmatic certainty of the priests and other devout Christians is just as evil as any demonic cult. Which is right? Both can't be right. Are both wrong? Perhaps. Every vice was once a virtue, and every virtue is probably doomed over the course of time to become a vice.
What a lot we humans are. Funny, grotesque, foolish, enlightened, smart, stupid, questing, despondent... Man is like a square circle, apparently contradictory in many ways, and yet he gets on all the same.