Who was Elymas/Bar-Jesus in Acts 13?

Bar-Jesus, also called Elymas, was a Jewish sorcerer and false prophet. He was with the Roman deputy Sergius Paulus and withstood Barnabas and Saul, trying to turn the governor away from the faith. Saul, filled with the Holy Spirit, rebuked him as a child of the devil.

Les teaches that at Paphos, on Cyprus, Paul and Barnabas found a certain sorcerer and false prophet who was a Jew named Bar-Jesus. He was with the Roman deputy or governor Sergius Paulus, a prudent man who called for Barnabas and Saul because he desired to hear the Word of God. This Jewish sorcerer, called Elymas in verse 8, was probably the governor's right-hand man. He withstood them, seeking to turn the deputy away from the faith. Saul, also called Paul, filled with the Holy Spirit, set his eyes on him and called him full of all subtlety and mischief, a child of the devil, an enemy of all righteousness, and one who perverted the right ways of the Lord. Les sees this as prophetic to a certain disease or degree.

Acts 13:6

And when they had gone through the isle unto Paphos, they found a certain sorcerer, a false prophet, a Jew, whose name was Barjesus:

Acts 13:8

But Elymas the sorcerer (for so is his name by interpretation) withstood them, seeking to turn away the deputy from the faith.

Why did Elymas oppose Paul and Barnabas in Acts 13?

Elymas opposed Paul and Barnabas because he sought to turn the Roman deputy Sergius Paulus away from the faith. As a Jewish sorcerer and false prophet, he withstood them to prevent the governor from hearing the Word of God and believing, perverting the right ways of the Lord.