Picture: An angel comforting Jesus, by Carl Heinrich Bloch, 1865–1890.
“Forget not to show love unto strangers: for thereby some have entertained angels unawares.--Hebrews 13:2
”The New Testament includes many interactions and conversations between angels and humans. For instance, three separate cases of angelic interaction deal with the births of John the Baptist and Jesus Christ. In Luke 1:11, an angel appears to Zechariah to inform him that he will have a child despite his old age, thus proclaiming the birth of John the Baptist. And in Luke 1:26 the archangel Gabriel visits the Virgin Mary in the Annunciation to foretell the birth of Jesus Christ. Angels then proclaim the birth of Jesus in the Adoration of the shepherds in Luke 2:10.
Angels appear later in the New Testament. According to Matthew 4:11, after Jesus spent 40 days in the desert, "...the devil left him and, behold, angels came and ministered to him." In Luke 22:43 an angel comforts Jesus Christ during the Agony in the Garden. In Matthew 28:5 an angel speaks at the empty tomb, following the Resurrection of Jesus and the rolling back of the stone by angels. Hebrews 13:2 reminds the reader that they may "entertain angels unaware".
Since the completion of the New Testament, the Christian tradition has continued to include reported interactions with angels. For instance, in 1851 Pope Pius IX approved the Chaplet of Saint Michael based on the 1751 reported private revelation from archangel Michael to the Carmelite nun Antonia d'Astonac. And Pope John Paul II emphasized the role of angels in Catholic teachings in his 1986 address titled "Angels Participate In History Of Salvation", in which he suggested that modern mentality should come to see the importance of angels.
As recently as the 20th century, visionaries and mystics have reported interactions with angels. In a biography of Saint Gemma Galgani written by Venerable Germanus Ruoppolo, Galgani stated that she had spoken with her guardian angel.