They deny the truths of the Bible. If you're denying the truth of the Bible, that is the spirit of antichrist. I do not say that lightly but as an admonition to those in the organization to compare the oaths they sworn with God's Word.
From these Masonic Service Association of North America's website [emphasis mine]:
Basic Principles. Freemasonry is not a religion, nor is it a substitute for religion. It requires of its members a belief in God as part of the obligation of every responsible adult, but advocates no sectarian faith or practice. Masonic ceremonies include prayers, both traditional and extempore, to reaffirm each individual's dependence on God and to seek divine guidance. Freemasonry is open to men of any faith, but religion may not be discussed at Masonic meetings.
The Supreme Being. Masons believe that there is one God and that people employ many different ways to seek, and to express what they know of God. Masonry primarily uses the appellation, "Grand Architect of the Universe," and other non-sectarian titles, to address the Deity. In this way, persons of different faiths may join together in prayer, concentrating on God, rather than differences among themselves. Masonry believes in religious freedom and that the relationship between the individual and God is personal, private, and sacred.
http://www.msana.com/religion.asp
Thanks to both of you for your helpful posts!!