Spells are not for devil worshipers. It is one common misconception of the society today. For spells as people see it is just like lasers or special effects just like what we see in movies and in television.
When a person practices magic and spells and first thing that they would say is, "He is an Anti-Christ." That would be rather offensive to the persons that you are talking about.
Anti-Christs are people that doesn't believe and like Jesus Christ. Spellcasters are not Anti-Christs because they believe and worship Jesus Christ himself.
Spells are practiced by these Spellcasters for protection, luck, revenge, love, money, and even for death. Most spellcasters would not want to teach others in their abilities for they fear that their student might attack them. For other reasons that a spellcaster teaches another person is that they need someone to learn their skills before they will be gone.
Spells are REAL. It cannot be seen by the naked eye of a person on how it works. But mostly you can see the effects of the spell when it starts to work. People may not believe in spells, but mind you people, the Spells believe in you.
Spells are not practiced just for fun. Most of the spells that is being cast is risky and has its own side effect. For it can either help an individual or it can harm them. So you just have to be careful in dealing in Spellcasters for they maintain the balance of good and evil in themselves. And you might not know of what is working on their clever little minds.