13:4 So, being sent out by the Holy Spirit, they went down to Seleucia. 
From there they sailed to Cyprus. 
13:5 When they were at Salamis, they proclaimed the word of God in the synagogues of the Jews. 
They had also John as their attendant. 

13:6 When they had gone through the island to Paphos,
they found a certain sorcerer, a false prophet, a Jew, whose name was Bar Jesus, 
13:7 who was with the proconsul, Sergius Paulus, a man of understanding.
This man summoned Barnabas and Saul, and sought to hear the word of God. 
13:8 But Elymas the sorcerer (for so is his name by interpretation) withstood them,
seeking to turn aside the proconsul from the faith. 

13:9 But Saul, who is also called Paul, filled with the Holy Spirit, fastened his eyes on him, 
13:10 and said, "Full of all deceit and all cunning, you son of the devil, 
you enemy of all righteousness, will you not cease to pervert the right ways of the Lord? 
13:11 Now, behold, the hand of the Lord is on you, and you will be blind,
not seeing the sun for a season!" Immediately there fell on him a mist and darkness.
He went around seeking someone to lead him by the hand. 
13:12 Then the proconsul, when he saw what was done, believed, 
being astonished at the teaching of the Lord. 

13:13 Now Paul and his company set sail from Paphos, and came to Perga in Pamphylia. 
John departed from them and returned to Jerusalem. 
 

vs 3-5 Seleucia was just a short distance to the west on the coast. Cyprus was where Barnabus came from. Salamis is on the east coast and Paphos on the west. So they just crossed Cyprus from east to west preaching in the synagogues as they went. At the time synagogues also served as hostels for intinerant Jews, and as such were ideal places from which Paul and Barnabus could spread the message.

The "John" that's mentioned here is John Mark, or more commonly "Mark" who later wrote the gospel of Mark.

vs 6-7 "Barjesus" (meaning "son of Jesus") may have been a name the sorcerer invented as a sort of anti-Christ figure. He misrepresented what Jesus stood for. This man was a Jew but sorcery was contrary to the Law of Moses and punishable by death. (Ex 22:18) As such, having a background in Moses, this man would be held more responsible than perhaps pagan sorcerers more ignorant of God. 

Sergius Paulus was a Gentile. And as such this would begin a significant shift in Paul's ministry as he was called not only to Jews but to Gentiles also. This man was spoken of as intelligent. But why was he with this sorcerer? There are many possibilities. For example the Jewish sorcerer, having heard the gospel and rejecting it, may have wanted to persecute Paul and Barnabus in an official capacity by complaining of them to the governor. But the governor may have also found what he was told to be interesting and so he called them in order to hear more. And thus the sorcerer was there in order to bear witness against them. 

vs 8-11 It is interesting to consider in today's atmosphere of free speech how to deal with those who opposed the Christian message and try to lead others away from the faith. Wouldn't it be nice if we could do as Paul and cast some miraculous curse upon them. But in fact this is more of the exception than the rule in Paul's ministry. For though he does do miracles throughout his ministry, it is never recorded that he ever does anything like this kind of miracle again. This is the only miracle in the New Testament I can think of that actually does harm to a person. (Other than when Paul himself was blinded, of which I will comment on further down and other than that done to Ananias and Sapphira).  Although the harm is only temporary and does bring positive results. But all other miracles involve healing or in some other way helping people. On the other hand considering Paul's previous violent temper in persecuting Christians, this was quite toned down. In fact I suspect that what made this incident unique was not so much the fact that this sorcerer was Jewish, for Paul would later be directly persecuted by Jews who tried to dissuade Gentiles from the faith, and yet he wouldn't respond in the same way. Rather I think that the Holy Spirit was gradually training Paul in the ministry. It was a sort synergistic relationship. Yes, Paul could take initiative as he saw fit and do miracles like this and the Lord's hand would be with him.  But that doesn't necessarily mean it was the most mature thing to do. 

I am reminded of an incident in 2Kings in which Elisha "as he was walking along the road, some youths came out of the town and jeered at him. "Go on up, you baldhead!" they said. "Go on up, you baldhead!"  He turned around, looked at them and called down a curse on them in the name of the LORD. Then two bears came out of the woods and mauled forty-two of the youths." (2Kings 2:23,24) It seems to me his temper got the best of him, but being a prophet God honored his word, and perhaps also with Paul.

It seems to me that if Sergius was an intelligent man then a simple debate should suffice. For what can stand up against the truth of the gospel? Rather than reasoning Paul blinds his opponent. Yet again and again we find later Paul reasoning against the Jews - even to the end of the book of Acts. And when speaking to the Greek philosophers in Athens, again we find Paul reasoning. 

I suspect that after this event Paul meditated on these matters with the Holy Spirit, and came to the conclusion that blinding your opponent was probably not the way to go about the ministry, even though it had produced a positive result. Perhaps this is one reason why the Holy Spirit led them to the island of Cyprus first - not only to communicate the message, but also to train the messengers.

But why this particular curse? Very simply it's the same kind of thing that happened to himself. For at one time was he not kind of in the sorcerer's place opposing the message and persecuting Christians? And what did God do to him? He blinded him! So perhaps he figured this was the kind of thing that should be done to those who oppose the message. But in fact his conversion itself was rather unique and was not intended as a pattern for evangelism, at least not in a literal sense.

vs 12 No surprises here. Who wouldn't have believed and indeed have even feared God greatly, having witnessed this event. But what was the quality of his faith we don't know. Blessed are those who do not see and yet believe. 

vs 13 Mark had enough and went home. This would be a cause for division even between Paul and Barnabus later on. For it is written of what occurred later in Acts that "Barnabas wanted to take John, also called Mark, with them, but Paul did not think it wise to take him, because he had deserted them in Pamphylia and had not continued with them in the work." Acts 15:37,38 But why did Mark desert them? Could it have been the blinding of the sorcerer that turned him off? Unlikely. The Apostles John and James would have loved to call fire down from heaven and burn up their adversaries. (Luke 9:54) And such miracles were not uncommon in the Old Testament of which Jews like Mark were quite comfortable. Rather I think it was because of Sergius being Gentile. And we later see that Paul would soon shift his focus almost entire to Gentiles. But Mark was still immature in his thinking of this mystery of the gospel of which Paul would write:   "This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus." Eph 3:6 This was difficult for many Jewish Christians like Mark to swallow at this time. Notice also that Mark went not to Antioch from which the Holy Spirit had initiated the call to this ministry, but to Jerusalem where he wouldn't have to face the music but rather be around people more emphathic to his desertion.  Interesting!  Coming back to Jerusalem meant deserting the minstry.  You're going to church, but have you deserted the ministry? To be ministers of Christ we must be willing to leave our comfort zone.

But in fact Mark would mature and become quite useful in Paul's ministry as Paul writes in his last letter to Timothy saying, "Get Mark and bring him with you, because he is helpful to me in my ministry." 2Tim 4:11