The New Testament uses both the words Satan and Devil as in original Greek Satanas and disbolos! There is no note-worthy difference between the two words. In fact, in the Gujarati translation Satan is used for both Satan and Devil. There are more than 60 references to the words Devil, Satan and Demon in the New Testament.
The word Satan or Devil has come to the New Testament from Old Testament and other Jewish literature. The word Satan means accuser in a court of law; but in most cases in Old Testament the word Satan is used figuratively and not literarily to indicate adversary.
Satan has many names in the New Testament. According to Jesuit biblical scholar John L. McKenzie, Satan is also called the strong one (Mt 12:29; Mk 3:27; Lk 11:21); the evil one (Mt 13:19+), the prince of this world (Jn 12:31). (Dictionary of the Bible, p. 775)
In the New Testament the most common word for Satan is devil used from the Greek word diabolos, meaning slanderer. In the Gospel according to John we find several reference to Satan by Jesus as the evil one, the father of lies, a murderer from the beginning. John has also called the evil one as the evil and Satan.
In the first three (Synoptic) Gospels we encounter Satan as the devil in person at the temptations of Jesus. The temptation is to be understood in the context of the divine voice at Jesus baptism: You are my own dear Son. I am pleased with you. (Mk 1, 11; see also Ps 2, 7; Is 42, 1; Mt 3, 17; 12, 18; Mk 9, 7; Lk 3, 22). This dramatic awareness is obviously connected with temptation. Mark gives the account of the temptation in just two sentences: At once the Spirit made him go into the desert, where he stayed forty days, being tempted by Satan. Wild animals were there also, but angels came and helped him (Mk 1, 12-13).
Perhaps Mark was not aware of the detailed account of the temptation of Jesus given by Mathew (Mt 4, 1-11) and by Luke (Lk 4, 1-13).
In the threatening atmosphere of the wilderness the devil appeared offering Jesus the means to escape the cost of his Messiahship. Biblical scholar Ronald Brownrigg says, The first three Gospels describe the inward struggle of Jesus to face the implications and manner of his Messiahship in the form of three direct temptations by the devil in person (Whos Who the New Testament, p. 247).
In the three temptations the Devil suggests wrong means to win over people in the display of his Messiahship.
Both in Mathew and Luke the first temptation is about bread. The temptations about the temple pinnacle and the mountain top comes second and third in Mathew account while in Luke the mountain top is second and the temple pinnacle is the last. Recent biblical scholars like John L. McKenzie, SJ says that the explanation of temptations is to be sought in doctrinal symbolism rather than in the real course of events. The episode (of temptations) describes the kind of Messiah Jesus was (Dictionary of the Bible, p. 879).
In whatsoever way we interpret the temptations of Jesus, it is clear in the Gospels that Jesus himself acknowledged the existence and power of a kingdom of evil under the control of Satan or Be-elzebul as he calls the devil in Mark (Mk 3, 22; see also Mt 9,34 & 10, 25). There are several instances in the Gospels where Jesus encountering Beelzebul and driving out the demons. Mathew and Luke narrate a case where Jesus driving out a demon that could not talk; and when the demon went out, the man began to talk. The crowds were amazed (Lk 11, 14 and Mt 12, 22-23).
The Gospels clearly show that Jesus not only cast out Satan but he also gave the power to his disciple to destroy the works of Satan. Luke gives the story of Jesus sending seventy-two men two by two to go ahead of him to every town and place where he himself was about to go (Lk 10, 1). When these seventy-two disciples return, they report to Jesus in great joy. They said, Lord, even the demons obeyed us when we gave them a command in your name (LK 10, 17).
The Apostles Peter and Paul and other New Testament authors like James and Jude shared the contemporarily belief in the Devil. Peter confronting Ananias and his wife Sapphira for their lie asks them why they have allowed Satan to take control of them making them lie to the Holy Spirit? (Acts 5, 1-11).
In his first letter Peter describes the Devil as a roaring lion. Peter writes, Be alert, be on the watch! Your enemy, the Devil, roams round like a roaring lion, looking for someone to devour. Be firm in your faith and resist him (1 Pt 5, 8-9).
St. Paul has acknowledged the Devil who he connects with the snake in the garden of Eden. He writes, I am afraid that your minds will be corrupted and that you will abandon your full and pure devotion to Christ in the same way that Eve was deceived by the snakes clever lies. (2 Cor.11, 3). St. Paul writing to Romans tells them, And God, our source of peace, will soon crush Satan under your feet (Rom 16, 20).
James has also refered to the Devil in his letter. He says, The demons also believe and tremble with fear. (Jas 2, 19).
But it is in the Book of Revelation we get a detailed discription of Devils persecution of the early Church. As Ronald Brownrigg writes, The dream-picture goes on to explain that the dragon, defeated in heaven, has been cast out into the earth. There, for a limited time, the war between good and evil will continue. (Whos Who the New Testament, p. 248).
The book of Revelation says, Then war broke out in heaven. Michael and his angels fought against the dragon, who fought back with his angels; but the dragon was defeated, and he and his angels were not allowed to stay in heaven any longer. The huge dragon was thrown out that ancient serpent, called the Devil, or Satan, that deceived the whole world. He was thrown down to earth, and all his angels with him And so be glad, you heavens, and all you that live there! But how terrible for the earth and the sea! For the Devil has come down to you, and he is filled with rage, because he knows that he has only a little time left (Rev.12, 7-9, 12).
The most important thing about Satan or Devil is that Jesus has defeated the evil one (see LK 11, 21-22; Acts 10, 38; Heb 2, 14).