I would think if God didn't rate sin and chastise his children, the believers Ananias & Sapphira would not have died for lying to the Holy Spirit (Acts 5:1-11).  That was a real extreme punishment as they dropped dead on the spot. Please notice that they didn't first become sick and later die.  Also I would think that if God didn't rate sin and chastise his children, no believer would become weak or sick or die from unworthily taking communion (1 Corin. 11:29-30) nor would Hymenaeus and Alexander have been delivered to Satan that they learn not to blaspheme (1 Tim. 1:20) and no brother or sister believer would be put out of the church for being a fornicator, an idolater, a railer, or covetous, or a drunkard, or an extortioner (1 Corin. 5:11-13), nor would a believer be told to reject a heretic in the church after a second admonition (Titus 3:10-11) nor would Jesus have promised to spue the lukewarm Laodiceans out of his mouth (Rev. 3:16) unless they repent.