Angels are mentioned one hundred and sixteen times in the Old Testament. The Bible without a doubt teaches that there are angelic beings.
Angels are created beings. Psalm 148:2,5 speaks of their creation. “Praise ye him, all his angels; praise ye him, all his hosts. Let them praise the name of the Lord: for he commanded, and they were created.”
The word angel means messenger, and in its Biblical use is sometimes used of God. The phrase, “Angel of Jehovah” is referenced to God Himself serving as a messenger to man (Genesis 16:1-13; 21:17-19; 22:11-16). Sometimes it is used of men (Luke 7:24; James 2:25; Revelation 1:20; 2:1, 8, 12, 18; 3:1, 7, 14). The word angel is sometimes used to represent departed spirits of men (Matthew 18:10; Acts 12:15). Even though the departed spirits of men may be called angels, the angels are not departed spirits of men. Nor do men at death become angels. The angels are a distinct order of creation. They are always masculine in gender. We never read of female or baby angels. Though angels are spirits (Psalms 104:4; Hebrews 1:14), power is given to them to become visible in the semblance of human form (Genesis 19:1,5; Exodus 3:2; Numbers 22:22-31). As to their number, the Bible says they are “innumerable” (Hebrew 12:22). Their power is inconceivable. In II Kings 19:35 one angel went out and “smote in the camp of the Assyrians an hundred and four score and five thousand; and when they arose early in the morning, behold they were all dead corpses.” The Bible mentions that angels have great wisdom (II Samuel 14:20).
There are only Three angels in the Bible that are named by name. Michael, the Archangel, whose name means “who is like unto God” (Daniel 10:21, 12:1; Jude 1:9; Revelation 12:7-10). Gabriel, whose name means “the mighty one”, and is the angel to whom has been entrusted various heavenly messages (Daniel 8:16, 9:21; Luke 1:19, 26-28). Lastly, Satan, whose name means, “to be the enemy”, and who is the archenemy of God and man.
Isaiah 14:12-14 describes the fall of Lucifer. “How art thou fallen from heaven, O Lucifer, son of the morning! How art thou cut down to the ground, which didst weaken the nations! For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north: I will ascend above the heights of the clouds; I will be like the most High.” The devil made himself a devil. By his own free act he lost his original supremacy and turned himself into a fiend. His great wisdom, corrupted by pride, developed into craftiness and wickedness. One third of all created angels followed Satan in his fall and became the fallen angels or Satan's angels (Revelation 12:4, 7-10).
The angels were created, as were all the heavenly hosts, by a simple command of God (Psalms 148:2-5). The angels are a distinct order of creation and have been given a heavenly position, or sphere, above the sphere of man (Psalms 8:5; Hebrews 2:7; Revelation 5:11; 7:11). There are two classes of angelic beings that are to be distinguished. There are God's angels or the unfallen angels, and there are Satan's angels or the fallen angels.
Demons are the fallen angels. Demons are Satan's angels. We are warned as believers not to seek out demons. Contact with demons is forbidden in the Scripture. Doors of contact are though wizards, mediums, witches, enchanters, prognosticators, astrologers, horoscopes, etc.
There are numerous names in the Bible for Satan. Satan is called:
1) The tempter (Matthew 4:3)
2) The devil (Matthew 4:5)
3) The enemy (Matthew 13:25,39)
4) Wicked one (Matthew 13:38)
5) The dragon (Revelation 12:9)
6) The old serpent (Revelation 12:9)
7) That crooked serpent (Isaiah 27:1)
8) The accused (Revelation 12:10)
9) The deceiver (Revelation 12:9)
10) The adversary (I Peter 5:8)
11) The liar (John 8:44)
12) The father of lies (John 8:44)
13) The murderer (John 8:44)
14) The oppressor (Isaiah 14:4)
15) The son of the morning (Isaiah 14:12)
16) Lucifer (Isaiah 14:12)
17) The roaring lion (I Peter 5:8)
18) The wolf (John 10:12)
19) The thief (John 10:10)
20) The strong man (Luke 11:21)
21) The angel of light (II Corinthians 11:14)
22) The god of this world (II Corinthians 4:4)
23) The prince of the devils (Matthew 12:24)
24) The prince of the power of the air (Ephesians 2:2)
25) The prince of this world (John 14:30)
26) The angel of the bottomless pit (Revelation 9:11)
27) Beelzebub (Matthew 12:24)
28) Belial (II Corinthians 6:15)
29) The anointed cherub (Ezekiel 28:14)
30) Leviathan (Isaiah 27:1), etc.
The Sadducees denied the existence of angels during New Testament times (Acts 23:8), but, of course, Jesus Christ affirmed the existence of angels time and time again (John 1:51).
God's angels have a special service to perform on the behalf of believers. According to Hebrews 1:14, the angels are “sent forth to minister to them who shall be heirs of salvation”. The Bible abounds in examples where we see the angels ministering to believers:
1) Provide for physical needs of believers, as in the case of Hagar(Genesis 21:15-19), and Elijah under his juniper tree (I Kings 19:5-7).
2) Preserve from danger, by taking Lot out of Sodom (Genesis 19:15,16), by watching over the three Hebrews in the furnace, and by watching over Daniel in the lions den (Daniel 3:24,25; 6:22).
3) Deliver Peter from prison and from the hand of Herod (Acts 12:7-10; Acts 5:19).
4) Direct the servants of God, as Philip, when he was to go to speak to the Ethiopian (Acts 8:26).
5) Reveal the Lord's plans, as in the examples of Daniel (9:21-23), Cornelius (Acts 10:3-6), and John (Revelation 1:1).
6) Announce happy events, such as the birth of John the Baptist, and that of the Lord (Luke 1:11-13; 2:10-12).
7) Encourage Paul in the midst of the anguish of the shipwreck (Acts 27:23,24).
8) Take the soul of Lazarus and carry it into Abraham's bosom (Luke16:22).
If you are not a believer, why not “Believe on the Lord Jesus Christ, and thou shalt be saved.” (Acts 16:31). Angels watching over you, among other things, are the additional benefits of our salvation.