Are there any subjects not discussed in a Lodge?
The two cardinal rules not to talk about in lodge are religion and politics, as Freemasonry is concerned specifically with neither.
This is an odd paradox in that fundamentally it promotes the individual connection to the Divine, but it admonishes us to not promote one belief system over another. Other topics such as work, family, business or other interests are openly talked about and should be amongst brothers as it builds our fraternal bonds.
In reality, the paradox is a harmonious balance. The reason for not allowing politics or religion to be discussed is the ideal. The practice of Freemasonry does promote and teach a sort of ecumenical philosophy of tolerance, which is the overarching idea. It does not imply one system of politics or religion is right or wrong.
Brotherhood members are forbidden - under penalty of Masonic irregularity - to debate or to engage in political issues or religious disputes.