"Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust. For if ye love them which love you, what reward have ye? do not even the publicans the same?  And if ye salute your brethren only, what do ye more than others? do not even the publicans so? Be ye therefore perfect, even as your Father which is in heaven is perfect." (Matthew 5:43-48)

Jesus sums up his rebuke of Pharisaical heresies with the foundational teaching of what it means to be the salt of the earth and the light of the world. 

To truly be a disciple of Jesus, we must love like Jesus loved. We ought to be acting compassionately for the benefit of others all around us. 

We are not to decide who does or who does not deserve our love. God sends rain and sunshine on the elect and the wicked. And He knows who is who! We do not know who is God's child and who is not. Therefore, we are to love everyone as our brother. 

Further, Jesus died for us while we were still His enemies. 

"For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life." (Romans 5:10)

The entire teaching of Jesus in this chapter can be fulfilled if we just love unconditionally as He loves us. 

In fact, we don't need to remember all the details of what to do or not to do as Christians. Love fulfills it all. 

"Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets." (Matthew 22:37-40)

By loving, we can be complete (perfect) disciples.