14We know that the law is spiritual; but I am unspiritual, sold as a slave to sin.
15I do not understand what I do. For what I want to do, I do not do. But what I hate, I do.
16And if I do what I do not want to do, I admit that the law is good.
17In that case, it is no longer I who do it, but it is sin living in me that does it.
18I know that nothing good lives in me, that is, in my flesh; for I have the desire to do what is good, but I cannot carry it out.
19For I do not do the good I want to do. Instead, I keep on doing the evil I do not want to do.
20And if I do what I do not want, it is no longer I who do it, but it is sin living in me that does it.
21So this is the principle I have discovered: When I want to do good, evil is right there with me.
22For in my inner being I delight in God’s law.
23But I see another law at work in my body, warring against the law of my mind and holding me captive to the law of sin that dwells within me.
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24What a wretched man I am! Who will rescue me from this body of death?
25Thanks be to God, through Jesus Christ our Lord!
So then, with my mind I serve the law of God, but with my flesh I serve the law of sin.
Romans 7
I'm going to stick with what Paul states. No one is sinless on the earth, Christian or not. We have a will and we have choices to make.
Further, John states you are liar if you think you have no sin or do not sin. Now why would he say that if a Christian does not ever sin or thinks they have somehow been perfected in the flesh?
We are going to be given new bodies and these old bodies are going to be done away with. And for the record, I am not making an argument for continuing in sin or practicing sin or sinning on purpose with the thought you just ask forgiveness after the fact. I am, however, making an argument for what scripture actually states and not some unbiblical teaching that states we are perfected in our flesh because we most certainly are not.
You cannot apply spiritual principals to something that is dead.