The word “Satan” appears in both the Old and the New Testaments. In the Hebrew of the Old Testament the word 'satan' is simply the ordinary word which means 'opponent' or 'adversary'. The word is used for anyone, or any being, which is an opponent. There is an example in the account of Balaam in the book of Numbers:
"But God’s anger was kindled because he went, and the angel of the LORD took his stand in the way as his adversary."
Here the word which is translated as "adversary" is the Hebrew word 'satan'. It applies to the angel, who is clearly acting on behalf of God. As the angel opposes Balaam it is described as an adversary, using the word 'satan'. The same thing appears in an even clearer way in two parallel passages in 2 Samuel and 1 Chronicles.
"Again the anger of the LORD was kindled against Israel, and he incited David against them, saying, 'Go, number Israel and Judah.' So the king said to Joab, the commander of the army, who was with him, 'Go through all the tribes of Israel, from Dan to Beersheba, and number the people, that I may know the number of the people.'” (2 Samuel 24:1,2)
"Then Satan stood against Israel and incited David to number Israel. So David said to Joab and the commanders of the army, 'Go, number Israel, from Beersheba to Dan, and bring me a report, that I may know their number.'” (1 Chronicles 21:1,2)
The same incident is being reported in both accounts. Notice, however, that in the Samuel account we are clearly told that it was God who incited David (the King of Israel at this time) to hold a census of Israel. In one account God is referred to as “The LORD” and in the other account he is referred to as “Satan”. The two words refer to the same being.
Quite clearly the Lord God is not a being who tempts mankind to sin. If one decides that the word 'satan' refers to a separate sinful being then there is a problem; but if one follows a biblical picture in which satan is simply an opponent, then the pair of passages make perfect sense.
Mankind has many opponents. One of them is our tendency to sin, which means that one might consider the devil to be an opponent, and in Bible times to apply the word 'satan' to it. There are, however, many other opponents, and the word 'satan' can apply to many things.
The New Testament is written in Greek. The problem for the Greeks was that the language contained many different words for opponent, depending on the kind of opponent indicated; the words are very specific. The New Testament writers were looking for a word to describe opponents of the Gospel and of the members of the church. None of the words available covered this idea so they took the Hebrew word and used that. By looking at the way it is used one can see that it doesn’t apply to a supernatural opponent of God.
"But he turned and said to Peter, 'Get behind me, Satan! You are a hindrance to me. For you are not setting your mind on the things of God, but on the things of man.'” (Matthew 16:23)
On this occasion Jesus had told Peter and the other disciples that he was going to be put to death in Jerusalem. Peter has tried to persuade Jesus that this need not happen. Jesus then describes Peter as an opponent, and he uses the word “Satan” to mean opponent.
It is quite clear that the word 'satan' is applied to Peter and not to some other being. The verse says quite clearly that the words are addressed “to Peter”. It describes his mind as being set on the things of man; not things of God, and not of some other being.
Another example appears in Paul’s first letter to the Corinthians
"you are to deliver this man to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord."
(1 Corinthians 5:5)
The young man concerned had committed some very wrong acts and was to be excluded from the congregation until he had repented of his actions. This included delivering him to someone who would oppose him: this might simply be the world outside the Christian community, or it might have been some particular person who was to teach him the right way. But it clearly wasn’t an evil opponent of God; the purpose of delivering the young man to this adversary was to make sure that he was saved at the day of judgement - hardly a fit activity for the main opponent of God.
As a final example, consider this passage:
"Among whom are Hymenaeus and Alexander, whom I have handed over to Satan that they may learn not to blaspheme." (1 Timothy 1:20)
Again, people who have left the path of real Christianity have been delivered to some opponent to learn the right way. In this case they are to learn not to blaspheme. The practice makes no sense at all if they are delivered to God’s evil enemy; this is hardly where they would learn not to blaspheme.
Clearly the word 'satan' applies to opponents of God’s people, and not to a supernatural evil entity.