I believe in God, the Father Almighty, Creator of Heaven and Earth, of all this is, seen and unseen.
Among those unseen things that God has created are what we call "angels". That angels exist is clear from Scripture as well as Sacred Tradition.
Angels are purely spiritual creatures, they do not have bodies, and are not constrained by bodies as we are. They are personal and immortal, just as we are. They have intellects and free will, just as we do. Because an angel's mind does not depend on a body, an angel cannot forget or get confused and his will is much stronger than ours.
It isn't right that we become angels when (...if!...) we go to heaven. Angels are different from humans. Our souls will be in heaven with the angels until the last day when our bodies will be raised and join our souls again.
Scripture, supplemented by Jewish and Christian tradition, suggest that there are nine orders of angels in the hierarchy of heaven:
The Bible is full of examples of God using the angels as protectors of His people, as guides and as messengers. The two angels who came to Sodom and Gomorrah, the Archangel Gabriel announcing God's will that His Son should become Man to the Virgin Mary, the Angels consoling Jesus in the Desert and in the Garden.
Before He created Man, God created the Angels. He gave them intellect and free will also. He created them to share with Him the joy of Heaven and so invited them to choose to do so. Satan was one of the Archangels. He is also called Lucifer, because he was the lightbearer, a highly honoured position. Satan made an irrevocable choice to reject Heaven and took many other angels with them to Hell.
"[The Red Dragon's] tail swept away a third of the stars in the sky and hurled them down to the earth." (Rev 12:4)
"I have observed Satan fall like lightning from the sky." (Luke 10:18)
"The angels too, who did not keep to their own domain but deserted their proper dwelling, he has kept in eternal chains, in gloom, for the judgment of the great day." (Jude 6)