In the Bible, to be Holy means always to be set apart. Children of God are regarded as holy because they were set apart for God to live for His glory and also to become more like Jesus Christ. Christian life in that sense, is all about pursing holiness. In this passage, we learn what it means to pursue holiness so that we become like our Heavenly Father and also like our Lord Jesus Christ.
In the Bible, God sets aside His redeemed people primarily to fellowship with Him and to glory Him by reflecting His character through His people in this world. God is glorified when His redeemed people show certain marks that remind the world about God and His kingdom. In this passage, we learn how sincere love for others and constantly fighting sin in our lives through repentance and overcoming temptation, are the ongoing marks of a true Christian.