/summa/SS/SSII/SS_Q93:
We must now consider the species of superstition. We shall treat (1) Of the superstition which consists in giving undue worship to the true God; (2) Of the superstition of idolatry; (3) of divinatory superstition; (4) of the superstition of observances.
Under the first head there are two points of inquiry:
(1) Whether there can be anything pernicious in the worship of the true God?
(2) Whether there can be anything superfluous therein?