Therefore you shall be perfect, just as your Father in heaven is perfect. (Matthew 5:48)
Church Pulpit Commentary states the following concerning this passage:
If we are apt to grow self-complacent, to thank God we are not as other men are, but far better, it arises from the low standards we set before us. Now our Lord lifts up our thoughts far above all the standards of earth. ‘Be ye therefore perfect, even as your Father which is in heaven is perfect.’ Many of us simply pass over and ignore the words as impracticable and impossible. ‘Perfect!’ we say, ‘perfect as God is perfect! Impossible. Imperfection marks everything, and must mark everything here below; it is Quixotic to expect we can attain that which is plainly above our reach.’ And so we quietly ignore the words altogether, and to the vast majority they are a dead letter. Yet spoken by our Lord they must have a real and important meaning. In worldly things, in arts and sciences, a high standard is of great importance. And in the spiritual life our Lord gives us what alone will make our life high and noble and pure; He gives us a high standard, the highest of all standards, the Almighty Father Himself.
- The true standard.—Christ bids us look above and see the real and the true.
(a) The perfect sanctity, the intense purity of God: dwelling in light unapproachable. For that all-holy Presence we have to prepare ourselves.
(b) His perfect knowledge. More and more then we must be ever seeking after truth.
(c) The perfect harmony and unity of the Divine perfections. We have so many ‘ragged ends’; many noble qualities, many false, unreal ones; much of the glitter and the flashiness which is only untrue and unreal.
Perfection is important to understand because it describes both our God and our standard. It is a standard set high, but also a standard to be reached. Remember it is a command, and God never commands His own to do, or in this case to be something, without providing the means to do so. The standard is the Sermon on the Mount. The standard is perfection. And only God can achieve that perfection in us.