The Masons are currently running a recruiting campaign via television and other means and targeting the men of Maryland by opening their lodges in the state to all inquirers on April 2. Can a man be a Mason and a Catholic in good standing? No.
"However, the matter was clarified when Cardinal Joseph Ratzinger (later Pope Benedict XVI), as the Prefect of the Congregation for the Doctrine of the Faith, issued Quaesitum est, which states: '... the Church’s negative judgment in regard to Masonic association remains unchanged since their principles have always been considered irreconcilable with the doctrine of the Church and therefore membership in them remains forbidden. The faithful who enroll in Masonic associations are in a state of grave sin and may not receive Holy Communion.' Thus, from a Catholic perspective, there is still a ban on Catholics joining Masonic Lodges."
"The denomination with the longest history of objection to Freemasonry is the Roman Catholic Church. The objections raised by the Roman Catholic Church are based on the allegation that Masonry teaches a naturalistic deistic religion which is in conflict with Church doctrine. A number of Papal pronouncements have been issued against Freemasonry. The first was Pope Clement XII's In Eminenti, 28 April 1738; the most recent was Pope Leo XIII's Ab Apostolici, 15 October 1890. The 1917 Code of Canon Law explicitly declared that joining Freemasonry entailed automatic excommunication. The 1917 Code of Canon Law also forbade books friendly to Freemasonry.
"In 1983, the Church issued a new Code of Canon Law. Unlike its predecessor, it did not explicitly name Masonic orders among the secret societies it condemns. It states in part: "A person who joins an association which plots against the Church is to be punished with a just penalty; one who promotes or takes office in such an association is to be punished with an interdict." This omission caused both Catholics and Freemasons to believe that the ban on Catholics becoming Freemasons may have been lifted, especially after the perceived liberalisation of Vatican II. For its part, Freemasonry has never objected to Catholics joining their fraternity. Those Grand Lodges in amity with UGLE deny the Church's claims and state that they explicitly adhere to the principle that "Freemasonry is not a religion, nor a substitute for religion."