Properly speaking, Freemasonry only has three degrees of initiation: entered apprentice, fellow craft, and master mason. These are modeled on the levels of membership within medieval stone mason guides, from which Freemasonry probably derives. Degrees past the third degree are conferred by other organizations, such as the Scottish Rite, in which degrees range from four to thirty-three.
Freemasons keep some of their activities closed to non-members, and that policy has led many to label them a "secret society," which in turn opens up Freemasonry (as well as related Co-Masonic organizations such as the Shriners and the Order of the Eastern Star) to a variety of conspiracy theories.
In truth, however, there are a great many organizations that keep at least some aspects of their activities secret, whether they are concerned with the privacy of members, trade secrets, or numerous other reasons. One might even say something as innocuous as a family gathering is closed to non-members, yet no one is generally suspicious of them. People have a right to privacy. Others do not have an inherent right to know everything their neighbors are doing.
Freemasonry as an organization does recognize the existence of Supreme Being, and new members are required to swear that they hold such a belief. Beyond that, however, Freemasonry has no religious requirements, nor does it teach specific religious beliefs. In fact, neither politics nor religion are to be discussed within a Masonic lodge, which makes defining Freemasonry as a religion to be rather absurd. Freemasonry is no more religious than the Boy Scouts, which requires members to believe in some sort of higher power.
Ironically, the affirmation of belief in a supreme being may have originally been added not to control the beliefs of members but to refute the accusation of Freemasons being atheists.
Various anti-Masonic writers have made a variety of claims over the years as to supposed religious beliefs being taught within Freemasonry, generally only at the very highest levels. Where they get this information is usually rather vague and often not mentioned at all. The fact that such accusations are only leveled at the highest degrees of Freemasonry makes it impossible for the average reader to contest such claims, which is a common hallmark of a conspiracy theory.