In Catholicism, you wouldn't call yourself a Witch, though the abilities and structures would be similar. Christian Mages would be learning the power of their God and his son, Jesus Christ (who promised to teach these abilities to his followers anyway).
There are *so* many magical threads to Catholicism. Some variants of folk Catholicism is honestly just as much magic as religion. Google curanderismo/curandero for a start.
Practitioners do rituals using the saints. They will erect glorious healing altars with Our Lady of Hope/Lourdes, etc. They preform novenas and light candles. They carry prayer cards and medals which have been magically fixed. They believe in intercessory prayer and light candles and pray for themselves and others.
They barter with the saints, as in traditional petitions to St. Expedite or St. Jude where one leaves an offering for an answered prayer. You ever notice people taking out those adds praising St. Jude? That's why - St. Jude likes to be "paid" by public accolade. Practitioners might manipulate them even, like taking the Baby Jesus out of the arms of a Saint Anthony statue until St. Anthony delivers on a promise.
Catholic folk healing is replete with candle work, hands-on healing work like rub-downs with holy oil and holy water, Hyssop baths, censing with burning resins.
There are outstanding amulets that are made by Catholic curanderos: glorious decopaged horseshoes with glitter and botanical curious glued to them. I used to make protection amulets with the Archangel Michael's sword as the centerpiece.
Taking a quick look around the room i'm sitting in, i have an Our Lady of the Miraculous in a blue wine bottle filled with plastic flowers, a Sacred Heart of Jesus prayer card inside a curio-filled plastic flask, a fantastic packet amulet that's the size of a large book of Santisma Muerte - actually, just look through my photos on my profile to see some amazing examples of Folk Catholic magical art that i'm fortunate enough to own.
Like i said, Google "curanderismo" - also try "Santisma Muerte." Don't get fooled by some of the Afro-Caribbean religions that also work with the saints, but instead use them as guises for African deities - that's a different thing, wonderful and amazing religions, but not Catholicism.
Here's a link to the magical correspondences of the saints with enough linked reading material to keep you occupied for quite a bit: http://www.luckymojo.com/patronsaints.html
When I told my close friends about magick, they were not scared (NOTE: Me and my friends are Catholics) instead they were fine with it, and they just said that it's amazing
