In the beginning, God created the angels. They are spiritual beings, made good. By free will, Lucifer (called the “bearer of light”) decided to rebel against God, and a war exploded (Rev 12:7). 1/3 of the angels were kick out Heaven (Rev 12:4). Lucifer became Satan. Bad/fallen angels became demons. Michael (called “who is like God”) step up in rank and become the defender of Heaven. Later, God created human beings at his own image (Gen 1:27). But Satan hates God for what He did, so he took the form of a serpent to trick Adam & Eve to join his plan instead of God’s plan (Gen 3:1).

The story of the Fall of Lucifer can be found in theses 3 biblical passages
ISAIAH 14:12 EZEKIEL 28:1 REVELATION 12:1

Isaiah 14:12
Ezekiel 28
Revelation 12

Now, since God created the angels, they must fit somewhere into the 6 days creations.
St Augustine of Hippo suggest this: they were created the 1st day, where Light represent the good angels, and Night the evil angels, and God separated them.

For when God said, “Let there be light, and there was light,” if we are justified in understanding in this light the creation of angels, then certainly they were created partakers of the eternal light which is the unchangeable Wisdom of God, by which all things were made, and whom we call the only-begotten Son of God, so that they, being illumined by the Light that created them, might themselves become light and be called “Day”, in participation of that unchangeable Light and Day which is the Word of God, by whom both themselves and all else were made. But between that light, which is the holy company of the angels spiritually radiant with the illumination of the truth, and the opposing darkness, which is the noisome foulness of the spiritual condition of those angels who are turned away from the light of righteousness, only He Himself could divide, from whom their wickedness (not of nature, but of will), while yet it was future, could not be hidden or uncertain.

– St Augustine of Hippo (City of God, Book 11, Chapter 9+19)

Angels also have hierarchy.

Some examples of real-life exorcism (all theses movies were based on real events):

Good angels

Michael (Rev 12:7)
Gabriel (Lk 1:19)
Seraphim (Is 6:2)
Cherubim (Gen 3:24)
Raphael (Tobit 12:15)
etc…

Bad angels (demons)

Satan
Baal (Nb 25:3)
Beelzebub (Mt 10:25)
Leviathan (Is 27:1)
Behemoth (Job 40:15)
Asmodeus (Tobit 3:8)
etc…

Sometime we ask ourselves, what are they afraid mostly?
Mary & Jesus.

Things to NEVER touch!
Even if we are “super religious”, it doesn’t take away the fact that exposure can lead to a open doorway of possibility of possession. The Church is very cautious about theses issues. A Catholic nun can also be a victim because her parents were involved with occult.

Let me explain with an example.
There’s a disease running out in the world. Specialists says there’s things to avoid if we don’t want to be contaminated. Even if you’re the healthiest person on earth, you’ll still get that virus. Let’s face it, we are fragile human being, we are mortals. Here’s a list of thing which real experts on demonology wants you to avoid: