I find that a good number of believing Christians and Muslims think that Satan literally exists and is a very real actor in the real world.
Is "Mara the Evil One, the Tempter" a rhetoric device in Buddhist tales -- a personification to enable the construction of a certain kind of parable?
Or is "Mara" understood by contemporary Buddhists as an evil being who actually exists in the physical plane that we inhabit?
There are 5 kinds of Maras. The fifth is Devaputta Mara who is an actual being(god) who controls a portion of the paranimmita-vasavatti heaven. But he is not similar to the Satan concept in Christianity. Mara is not an eternal being. Unlike Satan, Mara is not against doing good deeds. He at times encourages beings to do good deeds and prolong their Samsara. Mara is only against attaining Nibbana. It is a position taken up by different beings from time to time. During the time of Buddha Kakusandha who was the first Buddha in this eon, venerable Moggallana himself was the Mara(Dusi). The Mara during the time of Gautama Buddha is his nephew who took up the position when Dusi perished trying to attack the chief disciple of the Buddha Kakusandha.
There's a whole section in the Samyutta Nikaya, listing the Mara's encounters with the Buddha who was already enlightened. If Mara is merely a personification of defilements, there can be no encounters with enlightened beings as they have already removed all defilements. Refusing to accept Mara as an actual being seems to be nothing more than the discomfort of accepting the existence of heavenly and hell beings.
Of course, I can't speak for all modern-day Buddhists, but for myself, those that I have learned from, and those that I have known, we believe that Mara is the metaphorical personification of the forces that oppose enlightenment. I've not met any Buddhist who believes that Mara is a literal personal being.
Mara is simply the gatekeeper of Samsara, it wants to keep all life in an endless cycle of death and rebirth without beginning or ending. This cycle is full of unresolved karma and is full of suffering. Mara wants to keep you trapped in this cycle. It wants you to listen to evil thoughts and behave badly in life so you die. It absolutely hates people trying to escape from death and those who are enlightened. Think of Mara like this: Everything we see is the result of our thoughts. Now sit still, meditate, try not to think anything, seperate your thoughts in good and evil. You will find Mara soon enough... It will tell you "why am I sitting here doing nothing?". Where do you think that thought comes from?
I would go so far as to say that neither Christians nor Muslims agree that Satan is a real being in the material world. After all, during the Holocaust, some Christians hid Jews in their homes. If Satan was actually an invisible person with eyes and ears and feet and a mouth, surely it would have been impossible to hide Jews from the Nazis.
The Buddha spoke against the caste system; he spoke against astrology, horoscopes, palm reading, fortune telling, faith healing or prayers made for the sick. He spoke against holy lands, consecrated objects or lucky amulets. He never claimed to perform miracles. Whenever he spoke of gods or spirits, it was to teach people how to benefit from their example; you, too, can enjoy the good fortune of the gods.
Belief in an intervening devil is a fearful belief. The Buddha never taught people to fear a benevolent creator god, much less a devil.
