Divination by the use of card decks is not a game.
If you want to play a card game, buy a modern tarocchi deck, not a set of Rider-Waite cards or other occult-designed decks.
If you want a randomization device, you can use whatever normal decks of cards are laying around.
If you want a randomization of storytelling device, you can get all sorts of gaming event/story element cards.
And yes, I do think Charles Williams was an idiot for using Tarot as a story device; but he was a genius idiot and not you. So even if he got away with it (which is a good question to debate), it doesn’t mean you will. If an Olympic swimmer can swim the English Channel, that doesn’t mean you won’t drown if you try it while out of shape and unprepared.
Do not dabble in divination. It’s stupid and wrong, and it attracts bad company.