Here is an excerpt from Angels (and Demons): What Do We Really About Them? (Ignatius Press; 2004, sixth printing) by Peter Kreeft:
The Twelve Most Important Things to Know About Them
1. They really exist. Not just in our minds, or our myths, or our symbols, or our culture. They are as real as your dog, or your sister, or electricity.
2. They’re present, right here, right now, right next to you, reading these words with you.
3. They’re not cute, cuddly, comfortable, chummy, or “cool”. They are fearsome and formidable. They are huge. They are warriors.
4. They are the real “extra-terrestrials”, the real “Super-men”, the ultimate aliens. Their powers are far beyond those of all fictional creatures.
5. They are more brilliant minds than Einstein.
6. They can literally move the heavens and the earth if God permits them.
7. There are also evil angels, fallen angels, demons, or devils. These too are not myths. Demon possessions, and exorcisms, are real.
8. Angels are aware of you, even though you can’t usually see or hear them. But you can communicate with them. You can talk to them without even speaking.
9. You really do have your very own “guardian angel”. Everybody does.
10. Angels often come disguised. “Do not neglect hospitality, for some have entertained angels unawares”—that’s a warning from life’s oldest and best instruction manual.
11. We are on a protected part of a great battlefield between angels and devils, extending to eternity.
