Anyone who is truly saved will have some good works, but if someone believes and then starts falling away, their failure will result not in the loss of their soul but in the loss of their rewards. I have a Bible study from I Cor. It is important to understand the importance of good works in regards to the rewards of believers and the possible loss of such rewards. If I already have eternal life because I already believe in Jesus, then my eternal life can never end. Eternal life cannot end, or it is not eternal.
Sin is serious and has very negative consequences.
God will chastise His children if they fail without learning to judge themselves and quickly confess. But when we are judged, we are chastened of the Lord, that we should not be condemned with the world. If I confess my sins swiftly when I need to, as a believer I will escape the judgment that God gives in this life to those who are His children. If I do not confess my sins now that I am a believer, then I will receive chastisement from the Lord. This chastisement is not the condemnation that unbelievers will receive.