Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes Our brother,  (2) To the church of God which is at Corinth, to those who are sanctified in Christ Jesus, called to be saints, with all who in every place call on the name of Jesus Christ our Lord, both theirs and ours:  (3) Grace to you and peace from God our Father and the Lord Jesus Christ. 

The first letter to the CORINTHIANS was written by the apostle Paul. This was an occasional letter – written in response to disturbing news of the state of the church Paul had founded in Corinth. Paul begins this letter by establishing his credentials as an apostle by THE WILL OF GOD.  He is establishing his authority and by extension the authority and truth of the gospel he preached.  In verse one  Paul also established his brotherhood in Christ with Sosthenes who was the former ruler of the Jewish synagogue in Corinth – a man much respected in that community  -to further underline his credentials

In Corinth some had doubts of the fundamental truth of the resurrection of Christ Jesus and there was apparently scandal in the lives of the Corinth Christians as well as in their worship.  Paul writes to those called to be saints through the blessings of God.  What he is telling them is that sanctification means separation from this world.  The Christians are reborn through faith in the resurrected Christ – and that belief guides behavior.  By Christ the Spirit is given to the called; not by man’s works but by the grace of God.  Holiness is the unmistakable characteristic of Christians and the church in Corinth was forgetting this.