Church teaching is clear — the Devil isn't mere allegory; he's real. The Catechism specifies:
Behind the disobedient choice of our first parents lurks a seductive voice, opposed to God, which makes them fall into death out of envy. Scripture and the Church's Tradition see in this being a fallen angel, called 'Satan,' or the 'Devil.' The Church teaches that Satan was at first a good angel made by God: The Devil and the other demons were indeed created naturally good by God, but they became evil by their own doing" (Catechism of the Catholic Church, §391, internal quotations and citations omitted).
Although the reality of Satan stretches back to the beginning of time, one of his main tactics throughout the ages has been to trick humanity into believing that he does not exist.
After all, it is harder to fight an enemy in which one doesn't believe.
Over the years, those who do not wish to believe in the reality of evil have made up many baseless theories in their attempts to disprove Satan's presence.
One of the most common demonological misconceptions held by some Christians is that the serpent from Genesis is not actually the Devil.
But the serpent who deceived Eve is, without a doubt, Satan, and this is revealed in both the Old and New Testaments. The Old Testament's book of Wisdom states, "But by the envy of the Devil, death came into the world" (Wisdom 2:24). In the New Testament, Revelation explicitly refers to "the old serpent" as the Devil and Satan (Revelation 12:9). This is repeated eight chapters later: "The old serpent, which is the Devil and Satan" (Revelation 20:2).
Turning back to the modern world, we see that ever since Satan was cast out of Heaven, the reality has been that "the whole world is under the power of the evil one" (1 John 5:19).
With the power (permitted him by God), Satan even tried to tempt Jesus, offering Him "all the kingdoms of the world, and the glory of them" (Matthew 4:8).
Today, instead of rebuking the Devil and his offer (as Jesus did), many have chosen to accept it. It's impossible for us to identify all of the people who have formally accepted the Devil's offer, but some famous entertainers have been on record about accepting his promise, through the years:
The Church defines sin as "an offense against reason, truth and right conscience," and, therefore, as "an offense against God." As with the infamous acts of Satan himself, sin "is disobedience, a revolt against God." The Church has long taught that there are seven "deadly" or "capital" sins:
Pride (which is in every sin) is judging oneself greater than one truly is and seeing oneself as the source of goodness. Avarice is an excessive desire to make and keep money or wealth. Envy is the desire to have something that is possessed by another, in such a manner as to wrongfully deprive others of it. Anger is an inordinate desire for vindication arising from unmoderated sorrow at some offense. Gluttony is eating to excess. And sloth, which is rooted in a lack of love for good, is a sluggishness of soul resulting from the exertion necessary for the performance of good work.
However, there are remedies for each of these sins. They are:
Humility is not adjudging oneself to be greater than one truly is; it is based on a true appreciation of one's position with respect to God and one's neighbors. Almsgiving is material or financial assistance given to the needy. Spiritual generosity is the joyful embrace of another's good fortune. Meekness is moderation in anger — the control of one's strength. Chastity moderates the desire for sexual pleasure according to the principles of faith and reason. Fasting is a form of penance that imposes limits on food and drink. And hungering for righteousness is the desire to know and do God's will.
God has made His will for man abundantly clear, telling us, "He who believes in the Son has eternal life; he who does not obey the Son shall not see life, but the wrath of God rests upon him" (John 3:36).
The wrath of God is what Satan and His followers must endure for all eternity. And although the Catholic faith has always taught clearly about the existence of Satan and Hell, this teaching often gets watered down.
Charles Baudelaire, a 19th-century French poet, summarized Satan's insidious plan by coining the famous phrase "the greatest trick the Devil ever pulled was convincing the world he didn't exist."
Watch the full episode of Mic'd Up—Who Is Satan?.