Why is it wrong to be a Master Mason?

Some churches and other religious groups have sometimes told their members that it is wrong to be a Freemason (of which Master Mason is one degree). Most often these views are based on misinformation or misunderstandings of what Masons stand for, or what their symbolism means. A religious group which opposes socializing with members of other religions or tolerating their presence will find itself opposed to Freemasonry's adherence to religious tolerance. This is probably the only legitimate reason for a church to oppose Freemasonry for its members.

Freemasonry is a purely voluntary organization (that's what the "free" part means) and any member who feels that he disagrees with the purposes, teachings or actions of the organization is free to quit at any time. Very very few members quit for this reason.