Actually, those who are born again are in fact perfect:
Hebrews 10:14
King James Version (KJV)
14 For by one offering he hath perfected for ever them that are sanctified.
Also Matthew 5:48 (YLT) where Jesus said....
"ye shall therefore be perfect, as your Father who [is] in the heavens is perfect."
According to Strongs, "perfect" is translated from the Greek τέλειος téleios, tel'-i-os; from G5056; complete (in various applications of labor, growth, mental and moral character, etc.); neuter (as noun, with G3588) completeness:—of full age, man, perfect."
Perfection in this case is not sinlessness, but a growing to spiritual maturity on the part of the ones chosen by God for a specific role in the Kingdom. (Revelation 20:6) Those taken into the New Covenant will be 'kings and priests' ruling with Christ in heaven, so this state of "completeness" is based upon their record as faithful Christians in every aspect of their earthly lives. It requires works to back up their claims of being footstep followers of the Christ. (James 2:24-26) They are commanded to carry on his work of preaching the "good news" (Matthew 24:14; 28:19, 20)
Understanding what "perfection" means is the hard part, though, not so hard, one must simply keep this statement in context of both the Chapter it is found in as well as the larger body of the Book of Hebrews.
Romans 5:1-2 YLT
"Having been declared righteous, then, by faith, we have peace toward God through our Lord Jesus Christ,
2 through whom also we have the access by the faith into this grace in which we have stood, and we boast on the hope of the glory of God."
The YLT puts it rather well I thought. Being "declared righteous" in spite of being in imperfect flesh is what Paul had in mind here. He lamented about the frustrations of a mind subject to Christ but a body subject to sin. (Romans 7:21-25) Where was Paul's "perfection"? Only when the sinful body is abandoned and a new spiritual body provided, would Paul experience true perfection.
This translation is questionable.
It was taken from The Complete Jewish Bible, perhaps less likely to bring in bias from the teachings of Christendom, which I believe the KJV often does.
I have a dislike for the KJV...sorry. It is more questionable than most others in its renderings in my experience.
Galatians 3:23-25
King James Version (KJV)
23 But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed.
24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
25 But after that faith is come, we are no longer under a schoolmaster.
The word rendered "schoolmaster" is misleading here. The word in Greek is "paidagōgos" and it means "tutor". A tutor of Bible times was generally, not the actual teacher, but the one who accompanied the child to and from school and possibly in other activities as well. He would turn the child over to the instructor. This continued from childhood to perhaps puberty or longer. He was to keep the child from physical or moral harm.
The Law was a means to an end and it reminded Jews every day that they were sinners in need of their Messiah and his Kingdom.
So while we might not be perfect in regards to progressive sanctification, we are in fact made complete in Christ, and because we are born again, which is the result of being brought into Eternal Union with God, we are able to walk in His statutes and keep His judgments:
It is not a guarantee of personal salvation however. Even those who once walked in God's ways can deviate and lose their salvation. (2 Peter 2:20-22)
Ezekiel 36:24-27
King James Version (KJV)
24 For I will take you from among the heathen, and gather you out of all countries, and will bring you into your own land.
25 Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you.
26 A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
27 And I will put my spirit within you, and cause you to walk in my statutes, and ye shall keep my judgments, and do them.
Exactly, no Christian can 'walk in God's statutes' without the aid of his spirit....and no one can come to the Christ without an invitation from the Father. (John 6:44) He chooses us as much as we choose him.
And just as a sidepoint...one of the things I dislike most about the KJV is the old terminology. Calling someone a "heathen" is rather insulting. "From among the nations" is so much more apt, and non condemnatory, don't you think?