Freemasonry demands of its members a belief in a Supreme Being, and the ceremonies do contain prayers but it provides no system of faith of its own. If you want religion, you must go to Church or Synagogue or Temple or whatever. Freemasonry can only encourage you to be a better Christian, Jew, Muslim, or whatever one's faith is.
We refer to spiritual writings as the 'Volume of the Sacred Law'. To the majority of British Freemasons the VSL is the Bible. There are many in Freemasonry, however, who are not Christian and to them the Bible is not their sacred book. They will therefore take their Obligation on the book that is regarded as sacred to their religion. Thus when the 'Volume of the Sacred Law' is referred to in ceremonies, to a Christian it will always be the Bible and to a non-Christian it will be the holy book of his own religion. Incidentally, we do not say 'Amen' at the end of prayers. Instead we say 'So must it be', or in fact, we use the old English 'So mote it be'.
In order to maintain harmony in the Lodge, one of the basic principles of Freemasonry is that the Lodge shall not discuss religion. The United Grand Lodge of England will not have friendly association with another Grand Lodge if they tolerate such discussion.