P. Sins Punished Without the Loss of Salvation
The sixteenth area of evidence of eternal salvation is the truth of Scripture that gross sins were punished, but never with the loss of salvation. For example, 1 Corinthians 5:1–5 describes a case where a true believer is living with and sleeping with his step-mother. Paul condemned this, telling the church that it must exercise church discipline to deliver such [a person over to] Satan for the destruction of the flesh. Notice that he says the flesh rather than the spirit, because the text goes on to say that the spirit [shall still] be saved. This gross sin was punished by excommunication, but not by loss of salvation.
A second example is 1 Corinthians 11:29–32, which deals with members of the Corinthian church who were misusing the Lord’s Supper. God disciplined them and punished them in several ways: weakness, sickness, and even death; but at no point did He threaten them with the loss of salvation whatsoever. So the biblical example is that gross sins were indeed punished, but never with the loss of salvation.
Excerpt from Dr Arnold Fruchtenbaum:
MBS102 ETERNAL SECURITY: Pg 16