The claims for devil worship etc come from mis-represented quotes from a handful of books, inwhich the author wrote their personal views, not that of Freemasonry. Even with this said, the persons opinion referenced the term lucifer, the morning star, but due to the teachings of a certain religion lucifer is deemed to be the devil.
So those who wish to say Freemasons believe Lucifer is the morning star are sort of correct.
The error is in what these same people believe lucifer is.
Lucifer means "Morning Star".
The most common application to Lucifer is the planet Venus, it is the translation from the Greek word Hesperos.
The Greeks saw Venus as two different entities, the morning star, which they called Φωσφόρος, Phosphorus, the "Bringer of Light" or Εωσφόρος, Eosphorus, the "Bringer of Dawn"; when Venus appeared in the Sky before the Sun. And Hesperos (Ἓσπερος, the star of the dusk) when Venus appeared first in the night sky.
Venus 'overtakes' the Earth every 584 days as it orbits the Sun. As it does so, it goes from being the 'Evening star', visible after sunset, to being the 'Morning star', visible before sunrise.
It is not the modern use of the term Lucifer.
Lucifer was then attributed to fallen Angels, not one but all fallen angels.
It wasn't until modern to late Medieval Christian times that Lucifer was associated to one fallen angel commonly associated with Satan, the embodiment of evil and enemy of God. It became a part of Christian legend and folklore and as we can see from the answers previously provided, people are blind followers to what they are told.
Reference to Lucifer and Freemasonry is most often attributed to the writer Albert Pike, with numerous mis-quotes from his book Morals and Dogma, another common masonic writer often, again misquoted, is Mackey.
Freemasonry even before Speculative times was a study of the Sciences, including Astronomy and those Freemasons who delve into the literal aspect of studying these sciences are fully versed in what Lucifer is, how the term came about, and how the term is mis-used in todays world thanks to legends taught in a religion.
Freemasons do not "believe" Lucifer is anything, especially not Lucifer of the Christian church ie Satan, they know that Lucifer is a name from ancient times associated with Venus and this understanding does not change from start to finish!!
For a look at the detail regarding the term Lucifer please see wikipedia for a more indepth explination.
http://en.wikipedia.org/wiki/lucifer...
The details regarding Lucifer and Freemasonry I detail, is what I learnt as a Freemason so I think I can talk with legimate truth over those who read kook sites on the internet.