For Pentecostals, spiritual and physical healing serves as a reminder and testimony to Christ's future return when his people will be completely delivered from all the consequences of the fall. However, not everyone receives healing when they pray. It is God in his sovereign wisdom who either grants or withholds healing. Common reasons that are given in answer to the question as to why all are not healed include: God teaches through suffering, healing is not always immediate, lack of faith on the part of the person needing healing, and personal sin in one's life (however, this does not mean that all illness is caused by personal sin). Regarding healing and prayer Purdy states: