Should we emulate Paul's use of allegory?
Paul's method of discerning parallels between the biblical narrative and the crisis facing his readers is invariably employed whenever preachers see the circumstances of their own day illumined or prefigured by the stories of Scripture. Thus all Christian preaching is allegorical in the Pauline sense. The function of preaching is not to give factual historical reports; rather it is to make metaphors, linking the ancient text with the present life of the congregation in fresh imaginative ways so that the text reshapes the congregation's vision of its life before God.
By that criterion, Paul's allegory in Gal 4:21-5:1 is a brilliantly successful piece of preaching...When allegory functions like that, in service of proclaiming the gospel, who can withhold the water for baptizing it? The key question is whether the allegorical reading is governed by the larger shape of the biblical story - as it is here in Galatians - or whether the method is drafted into the service of other conceptualities. Any interpretive method can be abused, including historical criticism. The tests of validity are finally theological rather than methodological (Galatians 309).