The distinction between passions and affections, long blurred under the generic label emotions, needs to be restored not only for the sake of orthodoxy, but also for the refinement of Christian sanctification and worship.
Recent evangelical theologies (e.g., Grudem, Erickson) have diminished the doctrine of divine impassibility in view of God’s manifest expression of feeling/emotion. Thomas Dixon’s research in his From Passions to Emotions: The Creation of a Secular Psychological Category suggests that responsibility for this diminution lies in the modern conflation of passion and affection, categories long distinct in Christian theology, in contemporary psychology.
William G. T. Shedd defines passion (lit. suffering) as an “impression upon a sensuous organism, from an outward sensible object, eliciting temporarily a sensation that previously was unfelt” (Dogmatic Theology, 165). Since God stands immutably outside his universe as its omniscient creator and sovereign, he has no passions: he is never surprised by or reactionary to the motions of his universe. Rather, his feelings and actions toward his universe are eternally predetermined, staid, and calculated. His dispositions, affections, inclinations, and disinclinations are deeply felt, but they are best described as responsive and responsible, never reactionary.
Creatures (and by theanthropic mystery, Jesus Christ) possess passions. We are neither sovereign nor omniscient, and we are frequently caught off guard by circumstances. But how should we express our passions? Jesus Christ is our model. He relentlessly domesticated his passions and responded chastely to his circumstances, experimentally converting his passions into measured responses flowing from his intrinsic perfections. Even his more violent responses (say, his clearing of the Temple grounds) are seen in retrospect to be calculated in their expression.
Christian sanctification may be defined in such terms. Sanctification is the filtering of the believer’s passions (πάθος) and lusts (ἐπιθυμία)—which can never be wholly excised in creatures—through the resident new nature such that they are expressed as biblically informed and measured responses. Jonathan Edwards understood this well in his Religious Affections, in which he regarded untethered passions as poisonous to religious awakening, but biblically cultivated affections as sustaining impulses.
With respect to worship, then, the foregoing suggests that rather than a passionate release of whatever feelings are incidentally possessed by the worshiper, we should privilege expressions of worship that are biblically informed (most especially by the affections commended in the psalms), carefully cultivated, and measured in their expression. This does not mean that Christian worship cannot be deeply felt or vigorously expressed; but the appellative passion should not stand as its principal descriptor.