Magic can be used outside of religious context. It can also be used within the framework of religions or spiritualities that allow the use of magic.
Christianity was never part of this.
1) The application of magic into any religious structure necessarily must assume that the religion itself does not prohibit the use of magic or witchcraft.
However, Christianity specifically and repeatedly clearly prohibits the use of magic and witchcraft. The same is of course true of Judaism. This is stated in very clear language in scripture as well as commentaries on scripture by their respective Talmudic and Church authorities.
Judaism and Christianity are revealed religions; this means the legitimacy of each religion rests solely on their sacred text, called "the word" in Christianity. They both believe their respective scriptures to be the only true revelations from their respective monotheistic supreme god. These are considered "revelations" that are stated in the Jewish Torah and in the Christian New Testament, sources that establish each religion's version of their respective "ultimate truth."
In Judaism, the prohibitions against witchcraft include Exodus 22:18, "Thou shalt not suffer a witch to live", and in Deuteronomy 18:10-11, "There must not be found among you anyone... practicing divination, or soothsaying, observing omens, applying sorcery, neither a charmer, a medium, a wizard, or a necromancer."
In Christianity, the prohibitions include Galatians 5:19-20 (King James Version) in listing "acts of sinful nature" which included the "worship of idols and witchcraft...", and in Revelations 21:8 that lists those destined for Hell which includes those that "practice witchcraft." There are others, but you get the idea.
These are just some examples of Jewish and Christian intolerance and myopic thinking that is incongruous to the higher ideals of pagan spirituality.
2) There are many reasons why it is not logical to try to combine Judaism or Christianity with Traditional Witchcraft. In fact, many members of both sides (Traditional Witches vs. Christians and Jews) would consider a practice that combined witchcraft with Christianity or Judaism with strong disapproval and even disgust. The main problem is the impossible task of accommodating directly conflicting fundamental beliefs.
3) Traditional Witches are pagans. We subscribe to Nature or Earth spirituality. Christians traditionally are somewhat fearful of Nature and to Earth spirituality because of Nature's closeness to the gods. Of course, they would use the word, demons. Christians approach nature with a great deal of apprehension specifically as a reaction to classical Neoplatonism of the Greco-Roman world and to ancient pagan civilization which exhibited a superior culture and a higher level of spirituality based on love, rather than the fear Christians needed to generate to herd people into their churches. Christians (Catholics) considered Nature as the domain of demons, which they considered to be evil spirits. However, the word "demon," is Greek for "spirit" not evil spirit. The Christians were affraid of spirits even though each person has a spirit, a.k.a.soul. This type of anti-rationalism is what helped to drove Europe into the Dark Ages.
4) Christians are monotheists, at least according to them. Classical Neoplatonists of ancient Greece and Rome questioned this idea as being ludicrous. Monotheism is defined as the belief in one supreme god. However, in Christianity, their one supreme god was declared to be three gods-in-one, a so-called "trinity" in the third century, C.E. That is 300 hundred years AFTER their Jesus lived. (Which means he never heard about a "trinity" and presumably would not approve.)
This trinity godhead is made up of 1) God the Father, 2) His "only begotten son" Jesus Christ, and 3) The Holy Ghost. This threesome may not sound like a monotheistic religion (because if you count them, there are three). Nevertheless, since the third century C.E., Christians have insisted that a trinity godhead is not polytheism. As a side note: Roman Emperor Julian Augustus called the Christian trinity, "the three-headed monster."
In any event, paganism and monotheism are not compatible.
5) Pagans take very strong exception
to the Christian idea that "God's only begotten son is Jesus Christ." This makes no sense as we believe we are all the sons and daughters of the gods.
6) Another claim in both Judaism and Christianity is the demand that their faithful follow no other god than the one their religious authorities approve. With this one point alone, it's obvious that the concepts of deity in Judaism / Christianity and those in Traditional Witchcraft hopelessly irreconcilable.
7) Then there are those other Christian pesky details, like:
• The expectation of being repentant of "sin",
• The disbelief in reincarnation, and
• The belief in the devil, otherwise known as Satan.
These are but three bizarre Christian beliefs that have no place in paganism because they are incompatible with traditional European spirituality.
8) Besides, those that are have pagan spirituality at heart could never accept Jesus as a "savior." We simply do not believe we are in need of being saved by anyone. In fact, pagans find the very idea absurd and arrogant.
If Judaism or Christianity is deeply meaningful to you, then live a Jewish or Christian life. Good people are in every religion.
Ultimately, you must decide which way of life you really wish. It is not always easy being a Traditional Witch, yet few Crafters would want to do anything else. But not everyone is up to it. It is only for a select few. When the time is right, you need to select the ONE PATH that is the true path for you. Then travel on that path with your chin held high and with a happy heart.