I recently heard an interesting view of the word “perfect” in Matthew 5:48. It reads, “You therefore must be perfect, as your heavenly Father is perfect.” (ESV)
The view I heard suggested that the word perfect was the opposite of using a hammer to drive in a screw. The screwdriver is the perfect tool for a screw, not the hammer. The hammer is intended for another purpose so it should be used for that purpose. You have to do the things God created you to do and not try to be someone else or do their work.
I think the view uses another definition of perfect than what Jesus meant. Jesus is demanding an impossibly great standard, one which you cannot attain but only through Jesus Christ can we attain to a perfection worthy of God. By placing our faith in Jesus Christ, God imputes Jesus’ righteousness to us (all His goodness is seen by God as though we did it).
The other view can be seen-through by substituting it into the verse: You must be the right tool for the job, as your heavenly Father is the right tool for the job. Apart from the strange sound of this revision it also brings to the forefront two things: 1) there is still a standard, the Father, up to which we have to measure, in either definition; 2) we are being called not to be something as well as to be something; there is a change involved – from what we are to what God is.
So, let us admit two things: 1) the perfection Jesus is talking about is a moral perfection (which He has just described in chapter 5 up to this point) that we can only attain through living our lives by faith in Jesus Christ; 2) the conclusion of the other interpretation is correct, just not for this passage but for one like Ephesians 2:10, “For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them.”