Angels are part and parcel of the biblical message from early in creation, from the book of Genesis all the way to the book of Revelation. We don’t simply see a flurry of angelic activity concentrated in the pages of the New Testament during the life of Jesus; we encounter them throughout the whole scope of redemptive history.
We have learned through modern science that there are realities out there beyond the scope of our ability to perceive them. Why is it that we believe that germs that we can't see are out there, but we have a bias that says there cannot be supernatural, heavenly beings—spirit beings—like angels, even though the Scripture texts are full of them?
The angels attend our Lord in the manifestation of His glory. But when the glory of God is eclipsed in a culture and in the church, as it is in our day, angels are dismissed as insignificant. When the glory of God is honored and the exaltation of Christ is upheld, we see attending those moments the heavenly host, who serve as an escort for the King.
—R.C. Sproul, excerpts from Unseen Realities: Heaven, Hell, Angels and Demons
Angels by R.C. Sproul (Teaching Series)
"Angels: Messengers and Ministers of God" by Phil Johnson
"Angels as Messengers" (Devotional)
"Angels and Demons Go Pop Culture" by Gene Veith
"Earthly Enforcers" (Devotional)
"The Heavenly Choir" by R.C. Sproul (Message)
"The Heavenly Host" (Devotional)
"No Little Angels" by Burk Parsons (Article)
"Servants of the Saints" (Devotional)