People in the Bible had no forewarning one would materialize. They didn't receive a text message at breakfast stating, "an angel will show up and talk to you at 10:00 this morning."
Of course, if you received such a text, you'd think you'd been hacked or someone had played a joke on you.
Angels appeared without warning to the main characters in the nativity narrative. The Israelites had been promised a king, a savior. The ancient, scrolled, Word predicted He would come as a baby.
Knowing a promise and experiencing it first-hand are two different ballgames.
Angels needed to prepare the people who would be directly involved with this miracle. An angel surprised Zacharias while he was fulfilling temple duties. The messenger told the priest he would have a son and to call him John. The angel left old Zack speechless.
The angel Gabriel appeared to Mary and later to Joseph. Gabriel explained what their roles would be as they brought Jesus into the world.
Zacharias, Mary, and Joseph, although scared out of their oatmeal at the time, committed themselves to believe the angel's messages.
Angels prepare us for what God has planned for us. They did a good job on the long-ago hillside with the shepherds. Can you imagine? Sitting around a campfire with your buddies, enjoying the night, telling stories, and making smores.
Suddenly a whole bunch of angels fill the skies and sing to you. What would you do?
Angels can appear as themselves. They can also take on human disguises. Sometimes you recognize them, but often, you don't.
Hebrews 13:2. Be not forgetful to entertain strangers: for thereby some have entertained angels unawares. KJV
Who knows? Maybe Sarah will visit you. She's a hoot and I promise you...she'll make you laugh. She'll also make you think. She's a delightful, fictional angel, but she might be real. She makes me chuckle with her antics. Look her up.
And have a Merry Christmas. Be an angel on earth to others.