Many consider masons satanists because they don’t require a specific belief in Christianity. Instead a belief in a supreme being (The Divine) 
With freedom of religion being a man’s natural right it would be improper to impose upon him any particular faith.
This is primarily in lodges that are recognized by the Grand Lodge of England.

Now as history and times change freemasonry is not without its own internal struggles & “scandals”.

The Grand Orient of France & UGLE split years ago as France began to allow atheists, satanists & women into lodges. 

Leo Taxil published a tell all revealing the secrets of the fraternity & after years publicly admitted to having fabricated the entire work.  He knew the controversy would sell.