John Calvin Commentary Matthew 5:45

"that ye may be sons of your Father who is in heaven: for he maketh his sun to rise on the evil and the good, and sendeth rain on the just and the unjust." — Matthew 5:45 (ASV)

That you may be the children of your Father who is in heaven. When He expressly declares that no one will be a child of God unless he loves those who hate him, who will dare to say that we are not bound to observe this doctrine? The statement amounts to this: “Whoever wishes to be accounted a Christian, let him love his enemies.” It is truly horrible and monstrous that the world should have been covered with such thick darkness for three or four centuries as not to see that it is an express command, and that everyone who neglects it is struck out of the number of the children of God.

It should be observed that, when the example of God is presented for our imitation, this does not imply that it would be fitting for us to do whatever God does. He frequently punishes the wicked and drives the wicked out of the world. In this respect, he does not desire us to imitate him, for the judgment of the world, which is his prerogative, does not belong to us. But it is his will that we should imitate his fatherly goodness and liberality. This was perceived not only by pagan philosophers but also by some wicked despisers of godliness, who have made this open confession: that in nothing do people resemble God more than in doing good.

In short, Christ assures us that this will be a mark of our adoption if we are kind to the unthankful and evil. However, do not understand that our liberality makes us the children of God. Instead, the same Spirit, who is the witness (Romans 8:16), earnest (Ephesians 1:14), and seal (Ephesians 4:30) of our free adoption, corrects the wicked affections of the flesh, which are opposed to charity. Christ therefore proves from the effect that none are the children of God but those who resemble Him in gentleness and kindness.

Luke says, and you shall be the children of the Highest. This does not mean that anyone acquires this honor for himself, or begins to be a child of God when he loves his enemies. Rather, it is because when Scripture intends to motivate us to do what is right, it frequently employs this manner of speaking and represents the free gifts of God as a reward. The reason for this is that such language considers the design of our calling: namely, that with the likeness of God having been formed anew in us, we may live a devout and holy life.

He makes his sun to rise on the evil and the good, and sends rain on the just and the unjust. Here, Christ quotes two instances of God's kindness toward us, which are not only well known to us but common to all. This very participation powerfully encourages us to act similarly toward each other, though, by a synecdoche,⁴²² he includes a vast number of other favors.

⁴²² “Combien qu'il comprend sous ces deux d'autres infinis tesmoignages, par une figure dont nous avons souvent parle, nommee Synecdoche.” — “Though, under these two, he includes innumerable other testimonies, by a figure, of which we have frequently spoken, called .” — “Though, under these two, he includes innumerable other testimonies, by a figure, of which we have frequently spoken, called Synecdoche.”