No,it's not worshipping the devil. Magic is changing one or more things into something diferent. Jesus is said to use magic; as did Moses! But magic has really nothing to do with religion,devil or otherwise.
Too long didn't read: Truth be told there's no evil in magic it's just that some people choose to use their magic for evil purposes.
Magic itself is a person's own will concentrated into a spell there's no harm unless it was made to harm because it was all made by the caster, it's just that there's been some deities that require an immoral tribute (not implying I worship them I just study them) and not many rules exist in the realm of magic you just need to know your way around magic and some people seek help from those said deities or other deities such as The Christian god to find the way and when they pray their god(s) Sometimes answer their requests for free and some require tribute but most of the powerful magic performed these days gets hindered by Earth's immense veil and to even perform such a spell requires hidden knowledge most of which can be found in the astral realm during an astral projection session.
magick [as in spell casting] is a neutral energy, its the caster who makes it 'good' or 'evil'. it has no specific deity worship. you could pray to a deity or you could just rely on the energy, it doesn't matter. if you are of a religion that is against magick and witchcraft, then you might run into some roadblocks, but magick can be done by anyone at any time, it comes down to your personal view if magick is 'evil' or not.
short answer, magick is neither 'good' nor 'evil' by nature. it is how you use it.