Our bodies belong to Jesus. Jesus has bought our souls or spirits with His Blood, and we are saved, but He has also bought our bodies with His sufferings. He died for your salvation, but he suffered for your healing. His body was broken for you, for the healing of your body. There is Salvation both for the body and for the spirit.
He's already paid for, not only your Salvation, but your healing. He shed His blood for your Salvation, and what did He do for your healing?--The Bible says, "By His stripes, His wounds, ye are healed!"--He suffered for your healing. So we can claim healing even as a part of His atonement. We can claim it as a part of what He paid for. He paid for it, it's yours already for the asking!
So if you've been sick and you need healing, ask the Lord to heal you, and take it by faith and it's there for you! God not only can do it, but He wants to do it! He's more willing to give than we are to receive! Believe God! He never fails! Hold Him to His Word! He says "Command ye Me!" (Isa.45:11) Have desperate prayer, and expect a miracle! You do your part, and the rest is up to God. "Ask and ye shall receive!" (Mat.7:7)