Scriptures describes this category of angels as follows:
Providers of Priestly Duties
Isaiah 6:1-7 “n the year that king Uzziah died I saw also the Lord sitting upon a throne, high and lifted up, and his train filled the temple. 2 Above it stood the seraphims: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly. 3 And one cried unto another, and said, Holy, holy, holy, is the Lord of hosts: the whole earth is full of his glory. 4 And the posts of the door moved at the voice of him that cried, and the house was filled with smoke. 5 Then said I, Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the Lord of hosts. 6 Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar: 7 And he laid it upon my mouth, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.”
Revelation 4:8 “And the four beasts had each of them six wings about him; and they were full of eyes within: and they rest not day and night, saying, Holy, holy, holy, Lord God Almighty, which was, and is, and is to come.”
There is not much scripture to describe the seraphim angels. In fact, the only time in scriptures that the word seraphim is used is in Isaiah 6. In Hebrew the word seraphim is the plural word of “saraph,” which means, “to burn.” We find from the passage in Isaiah that these angels resemble a lot like humanity.
We find that what Isaiah describes is an angelic category that praises God but not directly. In other words, they do not directly engage with God but call out to each other in God’s presence.
The words in Isaiah Holy, Holy, Holy are only used twice in scripture. These words are only spoken by Seraphim Angels in both places. When they are spoken, both times, they are spoken to someone transported in a vision to the throne of God.
The fact that the seraphim in Isaiah’s use of a three-fold repetition of God’s holiness is incredibly significant. This is called a “trihagion.” In ancient Judaism, the number “three” signified completeness and stability, connoting God’s wholeness as the beginning, the middle, and the end.
Announcing God’s holiness three times also connotes:
The eternal nature of God, which never changes. It is the same yesterday, today, and forever. Hebrews 13:8 “Jesus Christ the same yesterday, and today, and forever.”
The divinity of God’s perfection as seen in the Holy Trinity – the Father, the Son and The Holy Spirit. 1 John 5:7-8 “For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one. 8 And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.”
The completeness and supreme holiness are unmatched by anything or anyone else. Exodus 15:11 “Who is like unto thee, O Lord, among the gods? who is like thee, glorious in holiness, fearful in praises, doing wonders?” 1 Samuel 2:2 “There is none holy as the Lord: for there is none beside thee: neither is there any rock like our God.”
Isaiah goes on to tell us that when the seraphim proclaimed God’s glory that “the doorpost and thresholds shook, and the temple was filled with smoke” (Isaiah 6:4). In the ancient times, earthquakes and smoke were the signs of God’s divine presence. Exodus 19:18 “And mount Sinai was altogether on a smoke, because the Lord descended upon it in fire: and the smoke thereof ascended as the smoke of a furnace, and the whole mount quaked greatly.” Psalm 104:32 “He looketh on the earth, and it trembleth: he toucheth the hills, and they smoke.”
Agents of God’s Purification
When Isaiah noticed that the heavenly seraphim covered themselves before God to acknowledge their unworthiness before the Lord, Isaiah became aware of his own mortal sinfulness and feared for his own life. At that point, Isaiah tells us that one of the Seraphim picked up a burning coal “with the tongs of the altar,” and brought the live coal to Isaiah, and touched it to Isaiah’ lips (Isaiah 6:6-7). This act of the seraphim purified Isaiah’s sins by fire, as the seraph assured Isaiah that now his “guilt is taken away and his sin atoned for” (Isaiah 6:7).
With Isaiah’s sins cleansed, he could now speak directly to God. When God called out for a prophet – “Whom shall I send? And who will go for us?” It was only after Isaiah was purified that he was able to accept this prophetic commission to the people of Israel by responding – “Here am I. Send me!” (Isaiah 6:8).