There is nothing corrupt or sinful about the "fruits of the Spirit". Just because Jesus presents it to God united with His righteousness does not mean He must do so because it is corrupt and sin-stained and otherwise unacceptable to God. Not even Jesus can make something inherently corrupt and sinful acceptable to God. He first purifies the spring so that whatever flows out from it is pure and uncontaminated.

Deficient means immature (not corrupt and sin-stained). Perfect means the absence of corruption and sin. Perfection is progressive. Believers grow in perfection from perfection to perfection, from "one stage of perfection to another".

This “work of progression will not cease, but will continue throughout eternity.” (HP 186) “Even the most perfect Christian may increase continually in the knowledge and love of God. (ML 249) “And in heaven we are continually to improve. (COL 332) “The law of the Lord is perfect, converting the soul. Through obedience comes sanctification of body, soul, and spirit. This sanctification is a progressive work, and an advance from one stage of perfection to another. (ML 250)

You think that when a Christian is born again, his character is actually perfect and he has no longer any defects to be overcome, while I see actual perfection of character as a progressive work. It is only in Christ we are perfect, and through His imputed righteousness.

If we are indeed to overcome as Christ overcame, that we may mingle with the blood-washed, glorified company before the throne of God, it is of the highest importance that we become acquainted with the life of our Redeemer and deny self as did Christ. We must meet temptations and overcome obstacles, and through toil and suffering, in the name of Jesus, overcome as He overcame. (CON 66)

In short, man must overcome as Christ overcame. And then, through the victory that it is his privilege to gain by the all-powerful name of Jesus, he may become an heir of God and joint heir with Jesus Christ. This could not be the case if Christ alone did all the overcoming. Man must do his part; he must be victor on his own account, through the strength and grace that Christ gives him. Man must be a co-worker with Christ in the labor of overcoming. (AG 254)

Those who put their trust in Christ are not to be enslaved by any hereditary or cultivated habit or tendency. Instead of being held in bondage to the lower nature, they are to rule every appetite and passion. God has not left us to battle with evil in our own finite strength. Whatever may be our inherited or cultivated tendencies to wrong, we can overcome through the power that He is ready to impart. (AG 254)

The controlling power of appetite will prove the ruin of thousands, when, if they had conquered on this point, they would have had moral power to gain the victory over every other temptation of Satan. But those who are slaves to appetite will fail in perfecting Christian character. The continual transgression of man for six thousand years has brought sickness, pain, and death as its fruits. And as we near the close of time, Satan’s temptation to indulge appetite will be more powerful and more difficult to overcome. (CD 59)

The animal propensities should not be educated and strengthened to rule the whole being. (10MR 282) Said the angel: “Sacrifice all for God. Self must die. The natural desires and propensities of the unrenewed heart must be subdued.” (1T 507) The greatest triumph given us by the religion of Christ is control over ourselves. Our natural propensities must be controlled, or we can never overcome as Christ overcame. (4T 235)

As you can see, overcoming our inherited and cultivated defects, weaknesses, and imperfections means ruling them with a sanctified will and mind, keeping them under subjection, preventing them from resurfacing and reining over us. It has nothing to do with discovering hitherto unknown cultivated sinful character traits and crucifying them. We must "deny self as did Christ." "Our natural propensities must be controlled, or we can never overcome as Christ overcame."

When the soul surrenders itself to Christ, a new power takes possession of the new heart. A change is wrought which man can never accomplish for himself. It is a supernatural work, bringing a supernatural element into human nature. The soul that is yielded to Christ becomes His own fortress, which He holds in a revolted world, and He intends that no authority shall be known in it but His own. A soul thus kept in possession by the heavenly agencies is impregnable to the assaults of Satan. But unless we do yield ourselves to the control of Christ, we shall be dominated by the wicked one. We must inevitably be under the control of the one or the other of the two great powers that are contending for the supremacy of the world. (DA 324)

True conversion is a radical change. The very drift of the mind and bent of the heart should be turned and life become new again in Christ. (4T 17) That which was objectionable in the character is purified from the soul by the love of Jesus. All selfishness is expelled, all envy, all evil-speaking is rooted out, and a radical transformation is wrought in the heart. (RH 7-22-1890) The Lord requires perfection from His redeemed family. He expects from us the perfection which Christ revealed in His humanity. (CG 477)

No one can be omnipotent, but all can cleanse themselves from filthiness of the flesh and spirit, perfecting holiness in the fear of the Lord. God requires every soul to be pure and holy. We have hereditary tendencies to wrong. This is a part of self that no one need carry about. It is a weakness of humanity to pet selfishness, because it is a natural trait of character. But unless all selfishness is put away, unless self is crucified, we can never be holy as God is holy. There is in humanity a tendency to suspicious imagining, which circumstances quicken into lively growth. If this trait is indulged, it spoils the character and ruins the soul. (FLB 140)

We may have flattered ourselves, as did Nicodemus, that our life has been upright, that our moral character is correct, and think that we need not humble the heart before God, like the common sinner: but when the light from Christ shines into our souls, we shall see how impure we are; we shall discern the selfishness of motive, the enmity against God, that has defiled every act of life. Then we shall know that our own righteousness is indeed as filthy rags, and that the blood of Christ alone can cleanse us from the defilement of sin, and renew our hearts in His own likeness. {SC 28.3}

One ray of the glory of God, one gleam of the purity of Christ, penetrating the soul, makes every spot of defilement painfully distinct, and lays bare the deformity and defects of the human character. It makes apparent the unhallowed desires, the infidelity of the heart, the impurity of the lips. The sinner's acts of disloyalty in making void the law of God, are exposed to his sight, and his spirit is stricken and afflicted under the searching influence of the Spirit of God. He loathes himself as he views the pure, spotless character of Christ. {SC 29.1}

While abiding in Jesus, enlightened by the Spirit through eyes of spiritual discernment, ignorance is impossible.