What determines the quality of individuals is their nature. True, the Holy Spirit in a believer is most valuable but this is referring to Him and not the regenerate individual. It’s the nature that determines the outcome of one’s character, identification and person-hood because everything we do is the result of our nature. Animals do not possess the ability of autonomy as a human does because they have instinct instead of a nature, therefore, instinct directs animals and a nature directs humans.
Scripture teaches all humans since Adam are born with a sinful nature (Rom 5:12), so what makes the difference of an individual at regeneration?—the addition of a new nature or “new man” (Eph 4:24; Col 3:10), which now coexists with the old nature. What makes the new nature valuable?—it is created after the image of Christ (Col 3:10) and through it the Holy Spirit brings, not His life, but the life of the Lord Jesus (Gal 2:20; Col 3:4).
The “new man” or, new nature is not all you (the regenerate) but part of you because the “old man” or old nature is also still part of you. It’s not as though the believer’s nature is half of the old and half of the new, but it is mostly of the new because the Spirit opposes the old nature (Gal 5:17) and restrains it from further domination (Rom 6:12, 14).
Just as Satan “cannot cast out Satan” (Matt 12:26; Mark 3:23), “old man” cannot cast out old man; neither can the believer in his “new man” cast out the old man because as already indicated (Gal 5:17), it must be by the Holy Spirit. It is due to His opposition to the old nature in the believer, which is the “carnal mind” that cannot “be subjected to the law of God” (Rom 8:7), that the Father “worketh in you both to will and to do of His good pleasure” (Phil 2:13).
It has been well said that, "Love does not function according to the quality of its object, but according to its nature."