I have though the same things but I have come to the conclusion that God = Good and Good = God, Doing Good things is the work of God, So helping people useing tarot is a Good thing. There are things in the bible to support one view of tarot.....
There shall not be found among you anyone that maketh his son or his daughter to pass through the fire, or that useth divination, or an observer of times, or an enchanter or a witch, or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer.”Deuteronomy 18:10
BUT We can do the same and find things to support our side
Saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams...." Acts 2:17
There are many times like this when the bible conflicts its self. However it is up to you to make a choice. What do you feel in your heart? What feel good, what feels right? But dont let other choose for you.
If you are wanting to convert to another sec of Christianity that would be liking to Tarot I think Gnostic would be the best bet, they are the Mystic sec of chritians. But you dont have to change your faith just to read tarot.
Tarot is somthing you do not somthing you worship or pray to. IF the minsiter said you cant read tarot to predict the future tell him that you dont, you just take a educated guess based on the cards