The great public prayer of the Church for those who are ill is the Service of Holy Unction. This Service, is long and exceedingly rich in readings from Scripture, and contains numerous allusions to biblical figures who were healed by the power of God. It gives in concentrated form, the Church's teaching about healing.
This Service identifies Christ as the "Physician and Helper of the suffering," and invokes upon the sick person, through anointing, the grace of the Holy Spirit, Who heals both souls and bodies. Since God "mercifully gave us command to perform Holy Unction upon Thy sick servants," Christ Himself is spoken of as the "incorruptible chrism" Who in old times had chosen the olive-branch to show Noah that the Flood had abated. (From ancient times olive oil was used in the making of Holy Oil.)
At the time of the Flood, the olive-branch symbolized tranquility and safety; so now the priest prays that the Savior will, through the "tranquility of Thy mercy's seal [the anointing with oil]," heal the sufferer.
Acknowledging that illness sometimes comes through the activity of demonic powers, the priest asks: "Let no interposition of malignant demons touch the senses of him who is marked with Thy divine anointing." Showing that the Church also understands the connection between sin and suffering, the priest prays that through this anointing the "suffering of him who is tormented by the violence of passions" may be washed away.
This healing service explores many aspects of sin, suffering and healing; it is a profound and very exalted service of prayer and intercession. One very important point should be made here: During Holy Unction we beg God to remove the sickness—but, in place of illness, we ask Him to give "the joy of gladness" (anointing itself is spoken of as the oil of gladness in the Psalms), so that the formerly sick person might now "glorify Thy divine might." Therefore, one of the purposes of healing is to enable the sufferer to resume his healthy and active service to God. In token of this, the Savior's healing of Peter's mother-in-law is spoken of: whereupon the fever left her, and she arose and ministered unto them. This is very important for us to remember:
When we are set free from the torment of bodily sickness, we are expected to fill our mouths with praise of God and serve Him by amending our sinful ways and living from henceforth only for God and the world to come, counting this world as nothing.