One of the hardest verses for a young believer to understand is in Matt. 5:48 "Therefore you shall be perfect, just as your Father in heaven is perfect." Immediately most believers take this as a matter of trying to be a better person, attempting to remove old sinful habits that don't match their new calling to be sanctified in Christ. This isn't the first time this word "perfect" is given to us by God. "And when Abram was ninety nine years old, the LORD appeared to Abram, and said to him, I am the All-sufficient God; walk before me, and be thou perfect." The first verse was spoken by the Lord to people who did not know Him very well in a general sense and most people received it as a commandment or an ordinance. The second verse was spoken between two friends who knew each other for 24 years.
It would be hard to argue with the Lord about being perfect as he gives the sermon on the mount in front of thousands of people but what Abraham experienced was in a more intimate setting. God first appeared to Abraham when he was 75 years old and now he was about to turn 100. If I was Abraham I would have said "God don't you know me by now? Are we not friends? I'm not perfect. I can't even fulfill the promise you gave me in a way that makes you happy. I've lived on this earth for 99 years and I'm not getting any better I'm only getting worse, what do you mean when you say 'be perfect.'"
What did God mean anyways? How someone answers this question is very exposing in terms of what insight they really have concerning God's purpose. Let's be honest, do we really know what is going on here? Do we really know what God means, what He is saying? Doesn't God know that Abraham gave up Sarah to pharaoh and that he would have the same serious failure again later with the king of Gerar. Abraham doesn't even believe God initially when He says that he will have a child by Sarah and instead pleads with God asking him "Oh that Ishmael might live before You" (Gen 17:18). Abraham's faith wasn't perfect and neither was his testimony. What part of Abraham was perfect? Only the Christ that would be worked into Abraham would be the perfection God had planned for Abraham.
God did not need Abraham to do anything to fulfill His covenant with Abraham. When Abraham tried to do something by his flesh, his natural strength to fulfill God's covenant this only offended God. By this we see God needs Abraham but God does not need Abraham to do anything for God. If you are thirsty you need a cup of water. You don't need the cup to do anything for you. You simply need the cup to contain the water. If the cup was to try and help you fill it with water this would be troublesome. God needs a man on the earth to receive God's blessing and God's supply as the All-sufficient God. God needs to work Himself into this man so that Christ can be produced out of this man.
This is not easy to see in the bible in fact it is completely hidden. We shouldn't fault anyone for interpreting these verses some other way because what God is saying to Abraham, what God means when he says "be perfect" is hidden. 90% of Christians won't help you understand these passages telling you "to be perfect does not mean to be a better Christian, no to be perfect means that the God who is perfection is worked into us to produce Christ out from us. Only the Christ that is worked into us and lived out of us is the perfection God is seeking" This is straight from the ministry of Watchman Nee and Witness Lee but is this really in the bible?
God's covenant with Abraham is that God would give Abraham a seed and that he would be the father of many nations. The seed fulfills God's purpose. Who is the seed? Issac is the seed. Who is Issac? Issac is a type of Christ (Gal. 3:16 and note Gen 22:2 and note 1). But in order to do this God needs to first work Himself into Abraham. This matter of God working Himself into man is this in the bible? Without the new testament it would be impossible to see this. We need to put together a number of different verses to even begin to understand this.
Gen. 15:6 - And Abram believed Jehovah, and He accounted it to him as righteousness.
Rom. 4:9 - For we say, Faith was accounted to Abraham as righteousness
Rom. 1:17b - But the righteous shall have life and live by faith.
Rom. 4:12-13 - (we) walk in the steps of the faith of our father Abraham ... for it was not through the law that the promise was made to Abraham or to his seed ... but through the righteousness of faith.
Gal. 3:14 - In order that the blessing of Abraham might come ... that we might receive the promise of the Spirit through faith.
Gal. 3:5 - He therefore who bountifully supplies to you the Spirit ... does He do it out of the works of law or out of the hearing of faith?
Gal. 3:6 - Even as "Abraham believed God, and it was accounted to him as righteousness"
Gal. 3:7 - Know then that they who are of faith, these are sons of Abraham
Gal. 3:26 - For you are all sons of God through faith in Christ Jesus
Rom. 4:17 - as it is written, "I have appointed you a father of many nations" in the sight of God whom he believed who gives life to the dead and calls the things not being as being.
Gal 4:22-28 - Abraham had two sons ... one (Issac) of the free woman (Sarah) ... (who) was born through promise ... These things are spoken allegorically, for (Sarah typifies God's covenant) ... and you, brothers, in the way Issac was, are children of promise
Gal. 5:4 - you who are being justified by law; you have fallen from grace.
Rom. 6:14 - you are not under the law but under grace.
Gal. 3:18 - For if the inheritance is of law, it is no longer of promise; but to Abraham God has graciously given it through promise
Rom. 4:16 - Therefore the inheritance is out of faith that it might be according to grace, so that the promise may be certain to all the seed, not to that which is of the law only, but also to that which is of the faith of Abraham, who is the father of us all.
What bible do you have? In your bible does it have Abraham believing, being justified and receiving the Spirit as the divine life to be regenerated as a son of God and then growing in life by experiencing the God of resurrection to produce Christ by being joined to grace (typified by Sarah) and growing further in life by trusting and depending on the God of resurrection so that he can offer to God the Christ which was worked into him and was produced out from him through faith? Abraham is in fellowship with God. Abraham walks with God. Abraham intercedes for Lot. Abraham obey's God. Does he do all of this out from himself? Is his willingness to trust in the God of Resurrection and sacrifice Issac out from himself? Let's read again from the scriptures
Gen 22:5 - And Abraham said to his young men, Stay here with the donkey; and I and the boy will go over there, and we will worship, and then we will return to you.
Heb. 11:17 - By faith Abraham, being tested, offered up Isaac; indeed he who gladly received the promises was offering up his only begotten,
Heb. 11:18 - Of whom it was said, "In Isaac shall your seed be called'';
Heb. 11:19 - Counting that God was able to raise men even from the dead, from which he also received him back in figure.
Abraham believed in the God of resurrection for Issac to be produced and Abraham believed in the God of resurrection for Issac to be offered back to God for His purpose. What does "be perfect" mean in the context of Abraham's experience? How then do we now read Genesis 17 or Matthew 5?
Genesis 17:1 - Jehovah appeared to Abram and said to him, I am the All-sufficient God; Walk before Me, and be perfect.
Matthew 5:48 - "Therefore you shall be perfect, just as your Father in heaven is perfect."
To attempt to be perfect by trying harder to meet God's standards is the law. This verse is not telling us that we should keep the law by trying to improve ourselves to meet God's standards. It is telling us that perfection is a matter us believing that Christ has died so that we can have God as our righteousness so that we may have another life a higher life the divine life, and live by faith. God's covenant with us is to give us His life and this life is just Christ Himself who lives in us and lives out perfection itself. Perfection for the believer is not merely an attribute or an outward practice. Perfection is a person the most wonderful Christ. As we enjoy this marvelous Christ living in us we experience grace and this grace labors in us.
This is my paraphrasing of the below verses:
Gal. 2:21 - I do not nullify the grace of God; for if righteousness is through law, then Christ has died for nothing.
Gal. 3:11 - By law no one is justified before God ... "The righteous one shall have life and live by faith";
Gal. 3:21 - Is then the law against the promises of God? Absolutely not! For if a law had been given which was able to give life, righteousness would have indeed been of law.
Gal. 2:20 - I am crucified with Christ; and it is no longer I who live, but it is Christ who lives in me; and the life which I now live in the flesh I live in faith, the faith of the Son of God, who loved me and gave Himself up for me.
1 Cor. 15:10 - But by the grace of God I am what I am; and His grace unto me did not turn out to be in vain, but, on the contrary, I labored more abundantly than all of them, yet not I but the grace of God which is with me.
Christ's process of perfecting the believers in Hebrews chapter 10:
1 For the law ... can never by the same sacrifices year by year ... perfect those who draw near.
4 For it is impossible for the blood of bulls and goats to take away sins.
9 He then has said, "Behold, I have come to do Your will."
10 By which will we have been sanctified through the offering of the body of Jesus Christ once for all.
14 For by one offering He has perfected forever those who are being sanctified.
I highly recommend the ministry book the Crystallization-Study of the Epistle of James by Witness Lee which focuses on the matter of Christian perfection. In this volume brother Lee uses the phrase "genuine christian perfection" more than 20 times. What is "genuine christian perfection?" it is nothing more and nothing less than a believers experience of the Triune God in all of his riches and all of his divine attributes.