While our focus should be and will be on the New Testament teaching on sickness and healing, I want to start with the Old Testament foundation for the New Testament teaching. The N.T. writers were committed to their sacred Scriptures. Their theology and knowledge of God was shaped by them. Their knowledge was then further molded by their contact with Jesus and the implications of the New Covenant. The first thing we should point out is that God is the creator and, therefore, thoroughly understands the human body.  David writes, “For you created my inmost being; you knit me together in my mother’s womb. I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well. My frame was not hidden from you when I was made in the secret place. When I was woven together in the depths of the earth, your eyes saw my unformed body.” (Ps. 139:13-16)
A second concept from the OT is that sickness and death are the results of the fall (cf. Gen. 3), not from the hand of an omnipotent God whose creation was “very good” (Gen. 1:31). Other results were the pains of labor, hard labor, and sweat from working the fields.
Thirdly, the Old Testament writers were aware that sickness and death could be a disciplinary measure of God toward an erring member of his family. In the Song of Moses, God proclaims himself to be the only all-powerful God: “I put to death and I bring to life, I have wounded and I will heal” (Deut. 32.39).  The prospect of God’s discipline is usually expressed in conditional statements that is common in writing covenants, which Deuteronomy depicts.  The possibility of God’s protection is assured if they would trust and obey him. “If you listen carefully to the voice of the LORD your God and do what is right in his eyes, if you obey his commands and keep all his decrees, I will not bring on you any of the diseases I brought on the Egyptians. For I am the LORD, who heals you” (Ex. 15.26, cf. Ex. 23:25-ff at Sinai).
Fourthly, the Old Testament highlights God’s sovereignty and power to heal. No sickness, not even death, is beyond his power to overcome.
Moses took Yahweh at his word and called upon him to heal his sister Miriam of her leprosy and God healed her (Num. 12.13-ff). David described God as the one who “heals all your diseases” (Ps. 103.3).  When the prophet Elisha prayed to the Lord for the Shunamite’s son, he was raised from the dead (2 Kings 4.32-35). Still, death reigned from Adam to Moses (Rom 5:14) which implies that God did not always intervene to heal. For examples of illnesses that God did not cure, consider Isaac (Gen. 27.1), Jacob (Gen 32:25, 48.1); Ahijah (1 Kings 14.4), and Elisha (2 Kings 13.14). New Testament examples include Paul (2 Cor. 12:7-10); Trophimus (2 Tim. 3:20); and Timothy (1 Tim. 5:23).
In the prophets, healing was frequently linked with the social, political, and spiritual aspects of life. Hosea 14:4 promised spiritual blessings to the repentant. It reads, “I will heal their waywardness and love them freely, for my anger has turned away from them.” In chapter 11 and verse three God speaks of healing His people. The context is probably a reference to their deliverance from Egyptian bondage. In Jeremiah, we find the language of curing and restoring being used for the spiritual relationship that Isaiah and Jeremiah had with God (Jer. 3:22; 15:19).
Israel (Jer. 3.22) and Jeremiah himself (Jer. 15.19) had with God.
Finally, we notice the promise of well-being in the age to come for the Messiah would be a healer. This aspect of His rule is seen in Isaiah 30:26 and 35:5-ff.  The last reference refers to blind eyes being opened, ears unstopped, and the lame leaping like a deer, and the tongue shouting for joy. Isaiah 53:5 reads, “But he was pierced for our transgressions;  he was crushed for our iniquities;  upon him was the chastisement that brought us peace, and with his wounds we are healed. The healing is in the context of the cross. The thought of His wounds giving the sinner healing points to spiritual healing.  Similarly, Isaiah 61 describes the Lord anointing the Messiah to preach good news to the poor, bind the brokenhearted,  proclaim freedom for the captives, and release from darkness for the prisoners – to proclaim the year of the LORD’s favor. Certainly, the favor includes the well-being promised in the covenant for those obedient servants.