The Engel Scale was developed by James F. Engel as a way of representing the journey from no knowledge of God through to spiritual maturity as a Christian believer. The model is used by some Christians to emphasise the process of conversion, and the various decision-making steps that a person goes through before they become a Christian.
+5 Stewardship +4 Communion with God +3 Conceptual and behavioral growth +2 Incorporation into Body +1 Post-decision evaluation New birth -1 Repentance and faith in Christ -2 Decision to act -3 Personal problem recognition -4 Positive attitude towards Gospel -5 Grasp implications of Gospel -6 Awareness of fundamentals of Gospel -7 Initial awareness of Gospel -8 Awareness of supreme being, no knowledge of GospelThe original model was developed by James F Engel and Viggo Søgaard, although this was later refined by Engel, who added several ideas from behavioural science, and published it in his 1975 book What's Gone Wrong With the Harvest. According to this model, everyone is somewhere on this scale.
The Engel Scale has been criticised for its fixed linear approach and a number of people have since introduced modifications. One of these is the Gray Matrix by Frank Gray of Far East Broadcasting Company (FEBC International), which is a two-dimensional model showing progression along two scales: knowledge of the Gospel and attitude toward it.