To answer your question, not meant as a condemnation, not to insult anyone...
It is also not my intent to get into any debate about right or wrongness of Catholic objections to Freemasonry.
Aside from the well-known historical/political issues, real or perceived, the Catholic theological objection is summarized as follows:
The notion of "Undefined Deism" - the GAOTU is not explicitly the Judeo-Christian deity.
The taking of "blood oaths", with the promise of maiming others, or agreeing to be maimed themselves
One common objection heard is that these oaths are just symbolic, or in jest, to which the CC would then assert that the oaths are....
Oaths taken in vain - invoking god, or swearing before god something that is not true.
No individual priest or bishop may grant a dispensation lifting the excommunication for Masonic membership - let's call it for what it is - being told "not to approach the sacraments" is excommunication. Its not the formal proclamation commonly thought of, but it is no less binding. According to the CC, merely joining incurs
ipso facto excommunication.
I believe that one day the prohibition against Freemasonry will eventually be lifted.
Great discussion about the K of C and Freemasonry.
As a practicing and baptized Catholic I have a unique perspective on both along with the conflicts between the Roman Catholic Church in my area and my blue lodge.
Too lengthy to provide all the details but since October 2010 it has been a non-stop headache. Starting with a phone call from the Grand Knight of the local K of C council. Of course he got my cell phone number from the parochial school directory so thats been subsequently removed. The next phone call was from the parish priest, who admitted that he knew nothing about Freemasonry and had no idea why the Church disapproves but he knew I shouldnt belong. We agreed to disagree after an 90 minute conversation. I refused to meet in his office as that was a hostile environment. He subsequently refused to meet for lunch and absolutely refused to meet at the lodge so I could show him around and explain the symbolism. When asked how he knows I am a Mason, he told me that some parishoners had googled my name and it showed my involvement.
This has been followed with anonymous notes left on my truck. My truck has masonic stickers on it along with a Catholic War Veterans sticker so I am sure that kills the offended members. A year ago my wife was called into the Catholic school office where she works and has the diocesian lawyer instruct her to remove the blue slipper sticker off her truck or be terminated. She removed it as she loves her job and my daughter enjoys the school she attends.
This past December the school principal called one evening and asked if I could meet her at the school. Thinking she needed something fixed, I brought my tool box. She very bluntly told me that the parish priest had directed her to get information on my Masonic involvement. I refused to give her any information. Although we remain speaking acquaintences we are far from friends. It is also ironic that several parents have approached the school board to have my wife removed from teaching since her husband is a Mason and they are afraid that I will try to convert them. Convert them to what is a total mystery to me. The most vocal parent actually took her son to the Scottish Rite learning center for help with dyslexia this past year. She remains blissfully ignorant that the clinic is a Masonic charity.
Summary: the US Catholic Church is not friendly with Freemasonry. I am always at a loss to understand or explain why this division exists. I personally believe that what may have happened hundreds of years ago has little to no bearing on affairs today but that is a moot argument.
I love my Church and remain a devoted Catholic but its been difficult. Currently the US Conference of Catholic Bishops have initiated investigations on the Boy Scouts of America and the Girl Scouts of America alleging that they are counter to Catholicism. The allegation is that they do not require a belief in Jesus Christ as dictated by the Church. The same traits are shared by Alcoholics Anonymous and many organizations.
Galileo was excomunicated from the Catholic Church for his beliefs that the earth revolved around the sun. For 350 years he remained banned from the Church until 1992 when Pope John Paul II issue a statement admitting error on the part of the Church. I believe that someday, not in my lifetime, this will be the same for Freemasonry. I may not live to see it but I will pray for it to happen and I will remain a devoted Roman Catholic and a dedicated Freemason, Scottish Rite Mason, York Rite Mason, and National Sojourner.