“It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife.”
King James Version (KJV)
5:1 Fornication - The original word implies criminal conversation of any kind whatever. His father's wife - While his father was alive.
1Co 5:1 Impurity in the Church SUMMARY OF I CORINTHIANS 5: The Incestuous Person. The Discipline Commanded. The Old Leaven to Be Purged Out. Heinous Offenders Not to Be Recognized Socially in the Church. [There is] fornication among you. Licentiousness was one of the besetting sins of the Gentiles at this time. Purity of life was almost unknown. So far was unchastity from being held in disrepute that temples were everywhere dedicated to Aphrodite (Venus), and in Corinth at the time when Paul wrote there stood one with a thousand priestesses, harlots, a gigantic brothel in the name of religion. It is not wonderful that time was required to cleanse the church, formed of converts from these heathen, from impurity. Not so much as named among the Gentiles. There was in the church a still worse case than the Gentiles would condone; a man had taken, probably after the death of his father, his father's wife, his own step-mother. This sort of incest was condemned by Greeks and Romans (Cicero, "Oratio pro Cluentio").