Health, Wholeness and Healing are all part of the atonement that Jesus bought for us and so when we put unwavering faith in Jesus then pain and sickness cannot successfully come against us because He bore all our pains and By His stripes we have been healed.

This was foretold in the Old Testament by Isaiah who wrote in Chapter 53 of his book where a literal reading of verses 4 - 5 tells us this...

Isa 53:4 Surely He has borne our sicknesses, and He carried our pain; yet we esteemed Him plagued, smitten by God, and afflicted. 5 But He was wounded for our transgressions; He was bruised for our iniquities; the chastisement of our peace was upon Him; and with His wounds we ourselves are healed.

We can see this repeated for us in 1 Peter, Chapter 2, verse 24 and Jesus' life on earth shows us numerous examples of how He illustrared this fact.

1 Peter 2:24 .. who Himself bore our sins in His own body on the tree, that we, having died to sins, might live for righteousness; by whose stripes you were healed.

Just so we wouldn't think this was a mistake on Peter's part, Matthew states it also in his gospel when talking about Jesus' and how he bore our sickness (which included demonization) and our sins upon Himself.

Matthew 8:17 "He Himself took our infirmities and bore our sicknesses".