I call shenanigans. Neo-pagan, Wiccan, and other modern religions adopted those terms as having a religious meaning in the recent past, while the words preexisted in society and continued to evolve and have distinctive everyday connotations in mainstream language. Some similar examples are Clerical workers, who deal with papers instead of exorcisms, or Mage and Magi, which refer to figures in Christian traditions and in the Zoroastrian religion. Actually, as I understand it the word Magic owes it's root to a term for followers of the Zoroastrian Religion, so it could be argued that the use of Magi, Mage, or Magic, or any derivative term, should be banned as potentially offensive to the practitioners of a world religion, albeit one with a rather limited number of adherents.
Additionally, I would argue that Witches of various sorts exist in so many different mythological, fictional, fantastic, and cultural association that it would be unfair to forbid the use of all instances of the term on the grounds of it's use by certain religions.
Basically, while some religions use the term to describe their adherents, the term pre-dates that usage by centuries and is used to describe an astonishing number of characters from fantasy and mythology. What is the Baba-Yaga, if not a witch? What are the Norns? Hel? Hecate? What shall we call Madame Mim? Mab? Morgan La Fay?
The problem with trying to have magic but not religion is that, in my mind, the idea that magic and religion could be separate or different things is a very recent one, and not well developed in our source material. Gandalf was a Maiar, a semi-divine servant of the godlike Valar, who were in turn the children, partners, or students of Eru Illuvatar. Hell, Elminster, that old plagiarism, had a similar role. Elric has an evil Demon in his sword and deals with Chaos on a regular basis. Conan fights demons and Settite priests every other Tuesday at six. Allanon and Brona were Druids, and Bards, Skalds, and their various kin have at least as much of a religious role as a secular one. Odysseus couldn't have made it far without Athena, Herakles was a bastard son of Zeus, and Achilles mother was a demi-goddess. All dragons issue forth from Tiamat, Vampires are created when a corpse is denied a christian burial, and so forth. Almost every hero from Mythology is distantly related to one or more gods or demi-gods. They've all got divine patrons. They all fight off underworld demons or evil gods or something of the sort. It just sort of comes with the territory.
And now, titles for your wizard.
Thanadule the Unclean, Lavamancer.
Bridget, Mistress of this very small rock which she can propel through your brain at incredible speeds if you keep talking like that.
The Ineffable Gigant, First among the Monkeys
Bubba Loophoole the most wise and flatteringly attired
Master Tibald Gobledugook, Professional Dragon Wrangler
Riddler Davion Primus
Beldona Who Knows All Secrets
The Amazing Brawndo!
Dread Immati the Rising Boot of the Inevitable
Terribus Who Walks With Wolves
Grannar The Unfashionable.
The Hermit Myxlpyx.
The Most Wise and Honored Wizard, John Runcible, Master of Smoking Crater Mountain.
Torontognash the Impressively Depraved.
The Archlich Boneash, formerly Boneash the Deceased, Formerly Dave Runcible of Lansing, Michigan.
Gilgamesh, Student of Enki, in the tradition of the great school of Sumer.
Boron who does not speak the names of ghosts.
Wilco the Thrice Shaken.
