Depends what you mean by "believe." Belief isn't necessary in this case, as in terms of Tarot these things are used mainly as a method of categorizing symbolism. The Trumps are ordered according to the Zodiac and classical planets, and all the rest of the cards' attributions are based on them. In this way, the people who created Tarot in its present configuration sought to create a true system that would work, kind of like a purring machine.
In the same way, most modern decks are built on the structure of the Kabbalistic Tree of Life, about which, again, belief is unnecessary since it is merely a model upon which ideas can be superimposed.
What the attributions can be used for is determining the "energy" of the card, the abstract idea which the card reflects. For example, Mars is attributed to the Tower, but that has little to do with proper astrology per se. Mars in this case implies a disruptive force, upheaval and destruction. In the case of the Minors, it's the same thing, but in this case we see how the attributions of the Trumps interact. The title of the Five of Wands is the Lord of Strife. This is not arbitrary but is because of its placement at place number five on the Tree of Life (attributed to Mars, discussed earlier) as well as its own attribution of Leo in Saturn. Leo is a fire sign, expansive, creative, ruling while Saturn is attributed to the ideas of cold, death and structure. In this configuration, Strife is inevitable.
So, while I don't believe in either of these things in the classical sense, they still are the vocabulary upon which Tarot is built. You can speak the language without any need for belief.