What are the historic and current views of the Catholic Church concerning Masons?
The Roman Catholic Church has offered the most persistent opposition to Freemasonry. The Church has prohibited its members from being Freemasons since 1738. Since then the Church made it clear that membership in Masonic associations will lead to excommunication.
The Catholic Church accuses that the Free Masons incorporate Deism and Naturalism as part of their masonic beliefs. Both of these philosophies have been condemned by the Church as atheistic.
After the Second Vatican Council many thought that the Church was going soft on Free Masonry. Questions arose in particular because the 1983 revision of the Code of Canon Law removed specific mention of Freemasonry from Canon 1374, which penalized "person[s] who join an association which plots against the Church".
In response to these questions, the Church position was reiterated by the then Cardinal Joseph Ratzinger in 1983. Joseph Cardinal Ratzinger being the prefect of the Congregation for the Doctrine of the Faith, with the apostolic approval of Pope John Paul II, issued a Declaration on Masonic Associations, which reiterated the Church's objections to Freemasonry. The Declaration states:
The faithful who enroll in Masonic associations are in a state of grave sin and may not receive Holy Communion....
...the Church’s negative judgment in regard to Masonic association(s) remains unchanged since their principles have always been considered irreconcilable with the doctrine of the Church and therefore membership in them remains forbidden.
Responding specifically to the question of why mention of Freemasonry had been removed from the Code of Canon Law, Cardinal Ratzinger stated:
... this circumstance is due to an editorial criterion which was followed also in the case of other associations likewise unmentioned inasmuch as they are contained in wider categories.
That is, the editors chose not to list specific organizations by name, but rather to prohibit the entire category regardless of the names of individual organizations.
Many Catholics believe that the prophecy in revelation about the second beast (Revelation 13:11) is made about the Free Masons. But the Church has never openly made any such claims.
Catholics (and all Christians and people of goodwill) are called to do what is right in all circumstances and follow the dictates of a well formed conscience so there are a few serious problems with Free Masonry, most of which can be said of any secret society.
A group that promises a deeper unfolding of a mystery as you progress through the ranks means they believe there is something to know further beyond what God has taught in His Revelation. That's a violation of the first commandment; it is believing there is spiritual truth outside of what God has revealed.
Masons say they believe in a higher power, a great architect, and this wouldn't be any worse than the 12 step process for Addicts, except that it doesn't imply that the higher power is good or loving. Catholicism and most Christians teach that God is good all the time.
There are Catholic fraternal orders and non-Masonic fraternal orders that are licit and laudable for one to be a member of. But, being a member of secret society with bylaws that if followed take its members outside the social compact. Between Masons, to protect one another from the law, it is probable that ones yes may not mean yes and ones no may not mean no