Why does James say that we should call for and elder of the church if we get sick?

The period from the resurrection to the destruction of Jerusalem was a transitional period.

Firstly the Same message the Gospel of the Kingdom was still being preached from synagogue to synagogue right throughout the Roman world. God had spoken through John and through Christ calling Israel to restoration of their covenantal obligations under the Mosaic Law.

Secondly there slowly developed a second thread. The Gospel of the Grace of God to the Gentiles in which was he would bless them outside the Mosaic Covenant. There was a very big push to bring the new Gentile Believers in Christ into Judaism by Circumcision and Law observance. (This was just one of the battles Paul faced and his most lethal) This came to a head in Acts 15. Where the apostles agreed than Gentile believers were not required to convert to Judaism nor were they bound by the Mosaic law. This was an important event in the life of Christianity. Christianity broke free from Judaism. However, That’s not the whole story yet.

The third aspect of this transitional period is that While some Jews ceased to keep the Mosaic law. And that was ok. And Gentiles were not required to keep the Mosaic Law And that was ok too. What about whole Jewish communities some of whom accepted Christ as the Messiah. Well they were allowed to remain Jewish/Christians. In other words in family life, Social life, religious life and in commerce they stayed faithful to Judaism. However not because Judaism saved them. It didn’t, Faith in Christ has saved them. But remaining outwardly a Jew meant that the Jewish families remained in tact. and Jewish life and commerce continued as normal. So we get for example people who still eat Kosher. Not because this brings Gods favour - it doesn’t. but because to do the contrary would break apart ordinary Jewish life.

Fourthly, The Apostles ministry was directed primarily at the Jewish Nation they were continuing the work that Christ had begun. and for 40 years From the beginning of John's ministry at Jordan right up to 70AD the message that Israel is to repent and return to the Lord still went out to this unfaithful nation. However in AD 69 the Legions moved in and the following year the Temple was destroyed and 1,100,000 Jews are killed in Jerusalem. Israel had had an opportunity to hear the call to repentance for 40 years and they had rejected their Messiah and his apostles.
Now while these apostles were going from synagogue to synagogue they could easily be silenced with on word. 'You are unrighteous'. In other words that do not keep the Mosaic Law. This would silence then in a moment and render their message of no value. Therefore Paul Timothy Silas Barnabas Had to be careful not to break the Mosaic Law. WHY? So that they could be saved? NO they were already saved. Was it because it was their duty as a christian? NO they as christians were not obliged to keep the law. They were free from the law completely. So why did Paul the greatest preacher of freedom from the Law keep it? - So that he might keep open the channels to the Jews to whom he was to preach the gospel of the kingdom. [1]
Have you fallen asleep yet? I hope not.

These Jewish/Christians were in a majority in some places. Now the second half of the NT contains a number of NT letters written to christians who also happened to be Jews too. They were saved good enough yet they still lived within Judaism and therefore they lived under the blessings and curses of the Mosaic Law. These NT letters written to Jewish/christians are... Hebrews, James, 1/2 Peter, 1/2/3 John, Jude, Revelation.

They all address christians - but Jewish christians. They all speak in terms of Law. Their emphasis is 'live righteously'.

So coming back to James.

James writes to Jews some of whom had got sick because God always disciplines Israel with sickness when they sin. And what is the cure? The cure is not with the doctors but with the Rabbis. They come to the sick. Teach them to repent of their sin and anoint them with oil symbol of the restoration of spiritual life and they get well.

This has no parallel in the Church today.

Steve

[1] 1 Corinthians 9: 20 And unto the Jews I became as a Jew, that I might gain the Jews; to them that are under the law, as under the law, that I might gain them that are under the law;
21 To them that are without law, as without law, (being not without law to God, but under the law to Christ,) that I might gain them that are without law.