Here is a post I just made on another thread, I feel it will help clear up most of your questions: "Firstly, I'd like to say I have not fully read the bible, nor am I Christian anymore. However, as Conjure has stated there is much magic in the bible. I'd like to say, in my honest opinion I see there to be a difference between the magic spoken of to be evil in the bible, and the magic practices of those who work with God. It reminds me of Act 7:22 "Moses was educated in all the wisdom of the Egyptians and was powerful in speech and action." The wisdom can be assumed to be magic, as in that time Egyptians were considered to be a very powerful nation of magic and the like. However, the magic he used unlike what the Egyptians used, was only used through him to God. Meaning, God performed the the magic, rather than the Egyptians who usually were the ones performing magic on the behalf of their gods. (Though I'm sure there is more than one insistence the Kemetic gods performing magic for people).
We see here that, while they are still "performing" magic, they are doing so only with the act of God, and without God's favor you can be nearly certain nothing will happen. I'm not saying of course, that people who work with the bible never use energy of their own, however I consider that when they work with God, or the saints, that they send their energy to God (Or to the saints which then send it to god), in which God then uses said energy (possibly adding his own) to perform the magic.
Magic, witchcraft, and many other words also have different definitions now a days, mainly do to the personal understandings of the people in the different eras. As the world turns, we find more and more things to be considered magic (like prayer, which to some was not considered magic), and other things that once were saw as sorcery or witchcraft to not be. (Such as technology, and in some places women who had any sort of education were thought to be witches) Which can suggest that they may have meant magic in other terms than we understand.
Each person sees and works with their own aspect of their god. Yes, they still may be the same god, but like us Deities can have multiple sides to them. That is why it is between them and their God. Regardless if the bible says it or not, the bible is man made, and is flawed. If a person receives the word of their god for themselves, and is told they may practice, then that would take precedence over something written hundreds of years ago. After all, there is "proof" in the bible that even God can change. (Like how he felt sorry for flooding the Earth and made a pact not to do it again)
Again, I am not Christian, and this is all my view on the subject. I'm sure many others on here would have a very different view on many things I have said. And admittingly I may have gotten some facts wrong, but my point still stands."
However, I will go into each question more specifically to make it easier on you:
1)As you can tell from above, magic in terms has changed in understanding and what is considered under the title of magic is bound to keep changing as time goes by. If you pray to god, and receive a sign (a feeling or some other sign) that you are allowed to practice, then you are.
2)This is probably one of the most touchy subjects when it comes to Christians who are faced with other deities and paths. "You shall have no other gods before me" is a phrase which can be interpreted in many ways. One of the ways surely would condemn anyone who worshiped any other deity in any way shape or form. However, I believe it more to say do not put any god up higher than God. And that if God asks you to do something, you always put him first, even if it would effect said wishes of another god. (Hence not putting their worship or wishes before Gods worship and wishes)
3) You can explain it many ways, however it does not always mean the person will understand or accept it. In fact, many people are ignorant when it comes to other people's points of view. If you wish to explain it in a way that hopefully most would understand, say something like you are working with god or doing gods work. (Whatever feels right for the type of magic you do) Another things many people have gotten away with is explaining the things they do as "gifts" from God. As with many people say who practice healing and such for the good of their Church or community. It all depends on who you are talking to at the time, and what they would be able to better understand.