But one ambitious Saint Matthew member is reading a bit ahead and had a question about this verse at the end of Matthew 5:
[Jesus said:] "Be perfect, therefore, as your heavenly Father is perfect." (Matthew 5:48)The question: "How can we be perfect when we were born imperfect and subject to sin?"
Here's what I wrote in response [expanded just a tad]:
The term translated as "perfect" that Jesus used here is "teleios," which also can be translated as "complete" or "whole."
(At least one commentator points out that it can also mean true, sincere, truthful, or loyal, indicating that being "perfect" also means remaining steadfast loyalty to God, including, of course, God the Son, Jesus. This makes sense when considering Jesus' words in Matthew 24:13, where he tells Christians facing prospect of rejection and persecution for their faith in Him: "...the one who endures to the end will be saved." The word translated as "the end" is related to the word translated as "perfect" in Matthew 5:48: In Matthew 24:13, it's telos; in Matthew 24:13, it's teleios.
The idea is to honor or keep the commands Jesus explains in Matthew 5:31-47 because of a desire to honor God.
When the Bible speaks of "keeping the commandments," there is a recognition that in our fallen nature, we human beings can't perfectly obey the law. Paul speaks for us in the New Testament book of Romans when he writes, "...with my mind I am a slave to the law of God [the commandments], but with my flesh I am a slave to sin" (Romans 7:25). Like David (and the rest of the Biblical writers), Paul knew that he, along with the rest of the human race, "was born guilty" (Psalm 51:5).
But keeping the law doesn't mean being perfect in obedience to God's commands. Only Jesus has accomplished that feat.
Keeping the law means honoring the law and invoking the help of God to obey.
Keeping the commandments also entails repenting for sin. So, in Psalm 139:23-24, David prays, "Search me, O God, and know my heart; test me and know my thoughts. See if there is any wicked way in me, and lead me in the way everlasting."
In a similar vein, John writes: "My little children, I am writing these things to you so that you may not sin. But if anyone does sin, we have an advocate with the Father, Jesus Christ, the righteous..." (1 John 2:1-2, see also 1 John 1:8-10).