The Bible isn't the most coherent of texts; it was written over a long time by many different authors. Much of what is attributed to certain people may not have been written by them at all. As such, there are many different stories with sometimes conflicting messages. For example, before the battle of Endor (not the one with the Death Star) Saul went to see a seer, in order to consult with the dead Samuel. Saul was punished for this because he was deliberately barred from the Lord's graces. The witch, however, was not, there is no mention of her after this.
The famous verse "thou shalt not suffer a witch to live" is unclear. Firstly, in the original Hebrew it refers specifically to witches, female ones, an anomaly. Secondly, it makes no sense in the context because the verses before it deal with the legal implications of sleeping with virgins and the one after it forbids bestiality. Hardly the place to deal with witchcraft.
There's also precedent for personal worship. Samuel's mother very much wanted a son and when she went to the temple to pray for one she did it in silence. The priests thought her crazy but didn't stop her. I would think Tarot falls into this last category. If someone believes then the messages of Tarot can only come from what they believe in. If someone is a Christian then all things stem from that.