I’m not saying that the BS are anti-Catholic. It is my understanding, based upon statements from then Cardinal Ratzinger in 1983 and 2000, that the primary reason Catholics cannot be freemasons is because masonry fosters religious indifferentism and is in effect its own religion, and therefore contrary to the fullness of truth. The secrecy of the organization has also been a consistent concern. That being said, I’m not claiming to have a perfect understanding of all the reasons masonry is prohibited and we might get on a bit of a tangent if we go into a lot of detail on that point. But, it is my understanding that the Church’s primary criticism of freemasonry is that it fosters religious indifferentism and that it is its own religion.
As far as proving my point, the Order of the Arrow is clearly freemasonry within Boy Scouts, I feel like that much is overwhelmingly clear. Again, the Order of the Arrow was created by freemasons that were active adult leaders in Scouting that wanted to create something very similar to masonry within Scouting. Both have 3 degrees, secret initiation ceremonies which have a religious dimension, members must vow to not reveal the secrets of the Order of the Arrow, there are altars, vestments and sacramentals, God is referred to as the Great Spirit (religious indifferentism). They both have a goal of self improvement for members.