God bless.
dreadnought, you forgot to add the remainder of the passage so as to hold context. It's no wonder you are confused about the passage if you take only the critical line of the passage. It's a though you ate the peanut butter without the toast and now your mouth is sticky and it's difficult to speak.
Even so, the passage can hold its own. This is about the Love for Enemies. Therefore, put yourself in context / situation (a memory of when) you "hated / disliked " a person and then read the passage again.
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Matthew 5: 43-48 (NIV)
43 “You have heard that it was said, ‘Love your neighbor and hate your enemy.’
44 But I tell you, love your enemies and pray for those who persecute you,
45 that you may be children of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous.
46 If you love those who love you, what reward will you get? Are not even the tax collectors doing that?
47 And if you greet only your own people, what are you doing more than others? Do not even pagans do that?
48 Be perfect, therefore, as your heavenly Father is perfect.
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And so, the point emerges clearer. Perfection, everyone knows, is impossible. Christians and non believer understand this (Born of sin through Adam and so on) and the fact that only God is (only He can be) perfect. First, you must understand that the Christ speaks from Heaven, not from Earth, through and with the Father. Therefore, the words of the Christ apply everywhere. In the hereafter, that is, Heaven, we will be made perfect (that is, born again in mind and body, full of the Holy Spirit).
Even in Heaven, this passage you mentioned will apply (emphasis - "you must be" and not "you will be").
Don't make the mistake that God will do everything for you. "You must" is an act of present practice and discipline. In the context of earth, the passage applies in light of the context. Even though you may be frustrated and are in state of anger, love your enemies, the Christ (Jesus) says, because the Father (and also the Son and Holy Spirit), while we were sinners and deserving of judgment, sent the Christ for salvation. This is an act that is perfect in itself.
To love our enemies does not mean to love their deeds, it means to care for them in their state of anger toward us et cetera. To be "Perfect" in this context means to go against the grain of sin. To conquer hate with love, which is in itself a perfect act because it defies all logic and sin. Remember to keep the context from which the passage is connected to.
Hope this helps.
It is so simple..
