It occurs to me that the entire concept of sin as an affront to God makes sin and fear inseparable. Apart from fear of God, sin in the traditional sense does not exist We can still behave badly but that poor conduct no longer qualifies as sin.
If as Jesus and the Apostle Paul taught, love is the supreme motivator, then fear of God and the whole concept of sin as a constraint on human behavior becomes obsolete. This is why Paul so vehemently proclaims the incompatibility of obedience to laws and the divine grace expounded in the NT. Laws are all about the fear of punishment. Any law system is predicated on the need to instill fear of punishment in people so as to coerce them into proper behavior. Thus sin and the law systems which define sin are fear based; without fear laws become meaningless along with the sins they delineate. Thus when Jesus proposed love as the only rule, he effectively did away with fear as a motivator and sin at the same time.
In reality no law has ever effectively restrained human conduct. The most fearful consequences have never prevented murders for example. What ultimately restrains an individual from behaving badly is their own conscience and its concept of what is justified as appropriate behavior. Undoubtedly we all can justify, at least in the moment, a host of actions which others see as objectionable or evil. Our moral compass is capable of immense compromise, especially when under stress and in perceived danger. The ever present law of reaping and sowing insures that there are always consequences to ever behavior, with or without any other law system.
I believe that the message of I Corinthians 13 is that there is no nobility or righteousness in behaviors which are motivated by fear, self promotion, or perhaps even guilt. Nobility and our divine nature can only be served and enhanced by behavior which flows willingly from a mind transformed by the example of Christ. Anything less is a renewal of sin and a rejection of Jesus.