God's definition of sin is much wider than ours, wherein we grade only murder, theft and other heinous crimes as sins, God has His own list which also includes hatred, partiality etc...
"but if you show partiality, you commit sin, and are convicted by the law as transgressors. " James 2:9 (NKJV)
Often we are partial either knowingly or unknowingly, however we cannot ignore this, we need to rectify, we cannot simply live with the so classed smaller sins which are our slipping stones to hell.
God wants us to be like Him and God has proven His impartiality through many live examples in the Bible and in our day to day life.
Jesus Christ has wonderfully summarized our required obedience and adherence to complete devotion to Himself and love for the neighbors.
The sin of partiality leads us to transgress God's law of “You shall love your neighbor as yourself," as is stated below :
" If you really fulfill the royal law according to the Scripture, “You shall love your neighbor as yourself,” you do well; but if you show partiality, you commit sin, and are convicted by the law as transgressors. " James 2:8-9 (NKJV)
Dear One! The Christian life is a privilege, however its a walk through the narrow way, we need to be careful not to slip onto the broad way of sin.
We need to be introspect ourselves according to God's Word and be obedient to the Holy Spirit in everything, for failing to do so will cost us an eternity in hell.