God sent "His own Son in the likeness of sinful flesh" (Ro 8:3) "who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him" (2Co 5:21). What is the likeness of sinful man? "The first man is from the earth, earthly" (1Co 15:47) and "so also are those [we] who are earthy" (:48). Physically it is heredity and DNA. Psychologically it is how you are raised, and as some presume, you become the product of the sum total of your experiences. Man is composed of "spirit and soul and body" (1Th 5:23). "The Lord God formed man of dust from the ground" (Ge 2:7) which is the body. The brain is a physical organ and we make decisions with our intellect. But you "believe in your heart" (Ro 10:9) which is from another capacity. That source is from when God "breathed into his nostrils the breath of life; and man became a living being" (Ge 2:7). Job said the "'Spirit of God has made me, and the breath of the Almighty gives me life'" (Job 33:4). You could limit God's creation if you only considered Solomon saying "they all have the same breath" (Ecc 3:19) or Isaiah stating, "Stop regarding man, whose breath of life is in his nostrils" (Isa 2:22). But a distinction is made by Solomon saying, "Who knows that the breath of man ascends upward and the breath of the beast descends downward to the earth?" (Ecc 3:22). He says "man goes to his eternal home" (12:5) and "the dust will return to the earth as it was, and the spirit will return to God who gave it" (:7). Zechariah states that it is the Lord who "forms the spirit of man within him" (Zec 12:1). He is the "Father of spirits" (Heb 12:9). Moses referred to the Lord as "the God of the spirits of all flesh" (Num 27:16).
God made man in the image and likeness of God (Ge 1:26). He "breathed into his nostrils the breath of life; and man became a living being" (2:7). Hebrew for "breath" means breath, wind, or spirit. "God is spirit" (Jn 4:24) and he communicates with man. Jesus "became a life-giving spirit" (1Co 15:45) and "breathed on them and said to them, 'Receive the Holy Spirit'" (Jn 20:22). "With the heart a person believes" (Ro 10:10) which is the "inner man" (Eph 3:16). It applies to "the hidden person of the heart" (1Pe 3:4) or "inner man" (Ro 7:22). You become a new person "inwardly; and circumcision is that which is of the heart, by the Spirit" (Ro 2:29). "'That which is born of the Spirit is spirit'" (Jn 3:6). Then "our inner man is being renewed day by day" (2Co 4:16). But since Christ was born as we are, wouldn't he become subject to the same fleshly drives? The difference is that "Christ is born of God" (1Jn 5:1). On the surface, as a man, it would appear that he possessed a sinful nature like everyone else, but he was sinless "for in Him all the fullness of Deity dwells in bodily form" (Col 2:9).