That you may be the children of your Father who is in heaven: for he makes his sun to rise on the evil and on the good, and sends rain on the just and on the unjust.
All Commentaries on Matthew 5:45 Go To Matthew 5
Augustine of Hippo
AD 430
it is to be understood according to that rule in virtue of which John also says, He gave them power to become the sons of God. For one is a Son by nature, who knows nothing at all of sin; but we, by receiving power, are made sons, in as far as we perform those things which are commanded us by Him. And hence the apostolic teaching gives the name of adoption to that by which we are called to an eternal inheritance, that we may be joint-heirs with Christ. We are therefore made sons by a spiritual regeneration, and we are adopted into the kingdom of God, not as aliens, but as being made and created by Him: so that it is one benefit, His having brought us into being through His omnipotence, when before we were nothing; another, His having adopted us, so that, as being sons, we might enjoy along with Him eternal life for our participation. Therefore He does not say, Do those things, because you are sons; but, Do those things, that you may be sons.