Contrary to the beliefs of some, there is nothing wrong with Masons.
If fact, there is much that is RIGHT with Masons.
While the Masons are to be commended on their charitable works, I disagree that there is "nothing" wrong with their organization.
From Scripture Catholic by John Salza:
Freemasonry is incompatible with Christianity because it promotes indifferentism. Indifferentism is the heretical belief that all religions are equally legitimate attempts to explain the truth about God which, but for the truth of His existence, are unexplainable. Such a view makes all truths relative and holds that God can be equally pleased with truth and error. Because Christians believe that God has definitively revealed Himself in the person of Jesus Christ, and desires that all men come to the knowledge of this truth, indifferentism is incompatible with Christian faith. Jesus said, "I am the way, the truth, and the life; no one comes to the Father, but by me." (John 14:6).
Freemasonry's teachings and practices also result in syncretism which is the blending of different religious beliefs into a unified whole. This is evidenced most especially by Masonry's religious rituals which gather men of all faiths around a common altar, and place all religious writings along side the Bible on the Masonic altar. This is also demonstrated by the Lodge's prayers and its unique names and symbols for God and heaven. Syncretism is the logical consequence of indifferentism.
The Lodge's practice of requiring its members to swear immoral oaths is also incompatible with Christianity. These oaths require a Christian to swear on the Holy Bible that he will uphold a code of moral conduct that prefers Masons over non-Masons, and to preserve secret passwords and handshakes. Such oaths are gravely immoral because their subject matter is trivial or does not give rise to the necessity of an oath. These oaths are also sworn under symbolic, blood-curdling penalties of physical torture and death called self-curses (e.g., having my throat cut across, and my tongue torn out by its roots). These penalties show a lack of respect for God and amount to blasphemy which is a serious sin.