Matthew 5:48

Let those women therefore look to it, who, by not holding fast the whole good, easily mingle with evil even what they do hold fast. Necessary it is that you turn aside from them, as in all other things, so also in your gait; since you ought to be "perfect, as (is) your Father who is in the heavens."

For as our sons after the flesh resemble their fathers in some part of their bodily shape, so do spiritual sons resemble their father God, in holiness.

And if ye salute your friends only, what do ye more than others? Do not even the publicans so? Be ye therefore perfect, even as your Father Who is in heaven is perfect. To love some men, that is, one's own friends, and to hate …

Therefore ye shall be perfect; as your Father who is in heaven is perfect - So the original runs, referring to all that holiness which is described in the foregoing verses, which our Lord in the beginning of the chapter recommends as happiness, and in the close of it as perfection.

Be ye therefore perfect, as your Father,....

If God's grace and goodness are (as they certainly are) his glory, then the glory of the gospel is the glory that excels, for grace and truth came by Jesus Christ, 2 Cor. iii.

Manifestly, our Lord here speaks, not of degrees of excellence, but of the kind of excellence which was to distinguish His disciples and characterize His kingdom. When therefore He adds, even as your Father which is in heaven is perfect--He refers to that full-orbed glorious completeness which is in the great Divine Model, "their Father which is in heaven." -- JFB40B.HTM --

We have here our Lord Jesus Christ’s rules for our conduct one towards another. He that would know how he ought to feel and act towards his fellow men, should often study these verses. They deserve to be written in letters of gold. They have extorted praise even from the enemies of Christianity. Let us mark well what they contain. The Lord Jesus forbids everything like an unforgiving and revengeful spirit. “I say unto you, that ye resist not evil.”

We have here our Lord Jesus Christ’s rules for our conduct one towards another. He that would know how he ought to feel and act towards his fellow men, should often study these verses. They deserve to be written in letters of gold. They have extorted praise even from the enemies of Christianity. Let us mark well what they contain. The Lord Jesus forbids everything like an unforgiving and revengeful spirit. “I say unto you, that ye resist not evil.” A readiness to resent injuries, a quickness in taking offense, a quarrelsome and contentious disposition, a keenness in asserting our rights—all all are contrary to the mind of Christ. The world may see no harm in these habits of mind, but they do not become the character of the Christian. Our Master says, “Resist not evil.” The Lord Jesus enjoins on us a spirit of universal love and charity. “I say unto you: Love your enemies.” We ought to put away all malice: we ought to return good for evil, and blessing for cursing. Moreover we are not to love in word only, but in deed; we are to deny ourselves, and take trouble, in order to be kind and courteous: “if any man compel thee to go a mile go with him twain.” We are to put up with much and bear much, rather than hurt another, or give offence. In all things we are to be unselfish. Our thought must never be, “How do others behave to me?” but “What would Christ have me to do?” A standard of conduct like this may seem, at first sight, extravagantly high. But we must never content ourselves with aiming at one lower. We must observe the two weighty arguments which our Lord uses to back up this part of his instruction. They deserve serious attention. For one thing, if we do not aim at the spirit and temper which are here recommended, we are not yet children of God. What does our “Father which is in heaven” do?

Be ye therefore perfect ... - The Saviour concludes this part of the discourse by commanding his disciples to be “perfect.” This word commonly means “finished, complete, pure, holy.” Originally, it is applied to a piece of mechanism, as a machine that is complete in its parts. Applied to people, it refers to completeness of parts, or perfection, where no part is defective or wanting. Thus, Job Job 1:1 is said to be “perfect;” that is, not holy as God, or “sinless” - for fault is afterward found with him Job 9:20; Job 42:6; but his piety was “proportionate” - had a completeness of parts was consistent and regular. He exhibited his religion as a prince, a father, an individual, a benefactor of the poor. He was not merely a pious man in one place, but uniformly. He was consistent everywhere. See the notes at that passage. This is the meaning in Matthew. Be not religious merely in loving your friends and neighbors, but let your piety be shown in loving your enemies; imitate God; let your piety be “complete, proportionate, regular.” This every Christian may be; this every Christian must be. Remarks On Matthew 5 1. The gospel pronounces blessings on things far different from what the world has thought to be a source of happiness. People suppose that happiness is to be found in mirth, in wealth, in honor, in esteem, in freedom from persecution. Christ says that it is to be sought in the reverse. Often people are most happy in poverty, in sickness, in persecution, when supported by the presence and promises of a merciful God. And if God appoints our station there, we should submit to it, and learn therewith to be content. 2. We may see the evil of anger. It is a species of murder. If secretly cherished, or exhibited by contempt and injury, it must bring down the displeasure of God. It is a source of misery. […]