If spirits do not exist in your religion?
Belief in spirits does exist in Biblical Christianity. Its the identity of the spirits that is at issue.
Who or what was expelled in Jesus' day if not demonic spirits who possessed individuals causing them much anguish? Jesus clearly said "expel demons" so their existence is not in question.
If not,
How would you interpret those who are "spirit mediums"?
Some people appear to have a certain 'something' (they often call it a gift) that the demons can tap into. Not everyone can be a "medium" which, as the name suggests, is a 'vehicle' for use by spirits masquerading as spirits of the dead. This happened in the case of apostate King Saul who wanted a spirit medium in Endor to conjure up the spirit of the dead prophet Samuel because God had abandoned him. He was the one, who under instruction from his God, had cleared all the spirit mediums out of the land....this was a lone survivor apparently, and only she saw and heard the supposedly "dead" Samuel.
Saul was desperate to know what was going to happen because no living prophets would speak to him.....why did he imagine that a dead one would, when Israelites had no belief in an immortal soul? (Ecclesiastes 9:5-1) He had lost the plot.
If they are not part of your religion, wouldn't you say people are faking not detesting god?
Huh? If you understand why God gave the commands he did in Deuteronomy 18:9-12, then you will see why any communication with spirits is forbidden. Demonic spirits are out to deceive, so the law was given to protect God's people from the practices of the foreign nations who incorporated all manner of spiritism into their worship. They were detestable to God because, like the spirit at Endor, they pretended to be from him and lead people away from God.
This is the reason why God sent his angelic messengers in human form to his servants. It is why Jesus appeared "in the flesh" to his disciples after his resurrection. They were forbidden to communicate with spirits. God made sure that they didn't have to.
How can you detest god by say using tarot cards when there are no such thing as spirits to which those tarot cards would work? They'd just be regular playing cards with lovely colored pictures.
Demonic spirits use any method humans can think of to deceive them....tarot cards is just one method. The spirits are real but they are not as 'friendly' as they pretend to be. Ask anyone who has tried to break free from them. The demons like nothing more than to mislead as many as they can, using any means available to them...especially religious superstition.
How can you divine, fortune-tell, do sorcery, and magic to something that doesn't exist in your faith?
Unless I'm wrong?
All of those things relate to demonic spirits, not the 'good' spirits who serve God faithfully. It is important to be able to make the distinction. The Bible clearly does.