Hamartano
is used a number of times in 1 Corinthians, but hamartia doesn’t come up until chapter 15. Paul first tells believers to flee from fornication because every other sin is outside the body, while sexual sin is a sin against one’s own body (6:18). But to marry is not to commit a sin (v. 28), and if a virgin marries, that is no sin (v. 28). If a man finds himself behaving in an unseemly way toward his virgin, he is not sinning by marrying her (7:36). This is probably not an instruction about a father and his daughter, and also unlikely to be referring to a young man with his betrothed. In the early church, there was a class of women called subintroductae, who were essentially celibate wives. The set-up was eventually condemned at the Council of Elvira, for all the reasons you might expect. This would explain why Paul here granted permission to marry if there was any hint of a moral problem. It would also explain why I haven’t preached through 1 Corinthians recently. I have enough troubles.
When it comes to debatable matters, Paul says that to sin against the brethren by wounding their weak consciences (8:12) is to sin against Christ Himself (8:12).
In chapter fifteen, Paul summarizes the gospel and says that Christ died for our sins (15:3). And if Christ was not raised from the dead, we are practitioners of a vain faith and are still in our sins (15:17). He then charges the Corinthians to awake to righteousness and sin not (15:34, hamartano). We have hope through the resurrection because the sting of death is sin (15:56), and the strength of sin is the law (15:56).