Being perfect in Christ is according to Col 2:10, 'For we are complete in Him. The word complete is pleroo, which means to be rendered full and perfect and that is positionally and not experiential or practical. There is a difference and we have to understand the difference so that we can relate to the truth in the right way and manner. That completion and being made perfect in Christ is instant the moment we believe upon the Lord Jesus Christ. We have a perfect standing before the Father through Christ and have been accepted in the Beloved (Eph 1:6). This is the confession of the NT believer who has been placed in Christ and hid with Christ in God (Col 3:3) with more than (60) references to this in the book of Ephesians alone. Any NT believer (both Jew and Gentile who make up the church) who does not accept their perfect standing before the Father and strives in their flesh to obtain unto that perfection through the law is misguided and being mislead and their capacity to grow in grace and knowledge of Christ will be hindered. Christ, as the head of the body (Col 1:18, 2:19), reigns within the heart of the believer, indwelling him through the Holy Spirit (Rom 8:10,11).
Rom 5:17-21
17 For if because of one man’s trespass (lapse, offense) death reigned through that one, much more surely will those who receive [God’s] overflowing grace (unmerited favor) and the free gift of righteousness [putting them into right standing with Himself] reign as kings in life through the one Man Jesus Christ (the Messiah, the Anointed One).
18 Well then, as one man’s trespass [one man’s false step and falling away led] to condemnation for all men, so one Man’s act of righteousness [leads] to acquittal and right standing with God and life for all men.
19 For just as by one man’s disobedience (failing to hear, heedlessness, and carelessness) the many were constituted sinners, so by one Man’s obedience the many will be constituted righteous (made acceptable to God, brought into right standing with Him).
20 But then Law came in, [only] to expand and increase the trespass [making it more apparent and exciting opposition]. But where sin increased and abounded (according to the law), grace (God’s unmerited favor) has surpassed it and increased the more and superabounded,
21 So that, [just] as sin has reigned in death, [so] grace (His unearned and undeserved favor) might reign also through righteousness (right standing with God) which issues in eternal life through Jesus Christ (the Messiah, the Anointed One) our Lord.
There's a 'corncob pipe full'!