Donald Bridge has some helpful things to say on this subject:-
1. Sickness is related to sin and to the fall. That does not mean that in individual illness is related to an individual sin. But it does mean that in broad terms, sickness is an enemy and a work of the Enemy. The idea of ‘wholeness’, on the other hand, is closely related to biblical concepts of holiness and of salvation.
2. Holy living is likely to lead to healthy living. Other things being equal, the Christian who keeps God’s laws is less likely to fall prey to certain physical illness (like cancer from cigarette smoking, ill consequences of over eating and over drinking, venereal disease, etc) and may well be more immune to psychosomatic illness caused by stress, worry, guilt, fear, loneliness, jealousy, and anger.
3. The gospel carries with it implications for changed life-style, changed attitudes, community acceptance and refuge from guilt, which may in turn have further consequences in mental, physical and emotional healing.
4. The church is the natural place in which this healing influence will be at work. If it conceded that ‘gifts of healing’ are available, then this is the place for their exercise – not necessarily in public on Sunday, but within the fellowship which is structured and led as it should be. Observation would suggest that a ministry of healing could have several possible expressions…
5. Satanic attack is a biblical reality, and there can be no reason for doubting that it still happens today. The Enemy may use an already-present ailment (physical or nervous) to sap faith and cloud vision. Especially where there has been dabbling in forbidden areas of the occult and so-called spiritualism, there can be a more direct demonic influence to which the victory of Christ over thee god of this world needs to be applied.
6. It is biblical to consider the possibility that some sicknesses may be the result of God disciplining the wayward child whom he loves. One would expect that removal of the disobedience would then lead to removal of the sickness.
7. Even if both apostolic gifts and more general charismatic gifts are abandoned as ‘not for this age’, we have the potentially awkward instruction of James 5:13-16 to cope with.
8. There can be no doubt that modern western Christians have become so accustomed to the ‘scientific thinking’ which permeates our society, that we experience real difficulties in accepting emotionally the concept of God’s direct intervention. Perhaps a clearer commitment to the biblical world-view will help here. It will involve (I have suggested) a glad acknowledgement of the sovereignty of God in all areas of life and activity. It will not try to maintain a strict dichotomy between ‘natural and supernatural’. It will point the physician back to the old concepts expressed in phrases like, ‘I bind up the wounds: God heals’. It will help him to recognise God’s goodness in some forms of ‘alternative medicine’ and in answered prayer.
9. Christian doctors, like all other Christians, must allow their faith to be challenged at times…
Based on Donald Bridge, Signs and Wonders Today, 191-194.