There are two approaches to Christianity (and perhaps to other religions). One is with a "metaphysicalizing impulse (MI)", and the other is a "pragmaticalizing impulse (PI)". Those with a PI are likely to take the central features of, say, baptism, matrimony and the Lord's Supper to be, broadly, pragmatic features: these liturgical actions are performatives in Austin's sense, which have normative and psychological effects. Those with an MI are likely to take the central features of these kinds of liturgical actions to be a metaphysical effect that provides at least partial truth-grounds for the normative effect and that supernaturally causes effects in the souls of those who genuinely participate.
It often seems like the difference between Christians who have the MI and those who have the PI has a basis in temperament more than anything else. To some people, metaphysicalizing comes naturally, and to others, pragmaticalizing comes naturally. The metaphysicalizers may accuse the pragmaticalizers of a shallowness and maybe sometimes a subjectivism. The pragmaticalizers may accuse the metaphysicalizers of a tendency to irrelevancy and maybe sometimes of using metaphysical speculation as a way to put off the hard work of living the Christian life.
Both metaphysicalizing and pragmaticalizing needs to be a part of Christian theology. That pragmaticalizing needs to be a part of Christian theology is clear from the fact that Christianity is not gnosticism. The Christian life is not a way of life centered on learning esoteric metaphysical claims, but is centered on living out the love for God in communion with others.
However, to neglect metaphysicalizing is to neglect a significant part of the difference between Old Testament and New Testament commandments. Some of the Old Testament commandments were normatively grounded merely in God's command. There is no intrinsic reason to avoid mixing different kinds of fabric in one's garments beyond the fact that God forbade it with his authority. Some of the commandments may have had a symbolic meaning, which was mysteriously fulfilled in the New Testament, and some may not have even had that. But the New Testament largely puts away the merely arbitrary and the merely symbolic divine commands (or, perhaps more precisely, transfers much of the authority over the merely symbolic to the Christian community, which then, as a diachronic and hierarchical community, gets to decide how exactly to celebrate that which God has put in place, with much more freedom—notice, for instance, how nobody thinks that in New Testament times God has very specific prescriptions for clerical dress, that being left to Church authority), focusing on that which is of intrinsic significance. If divinely prescribed central liturgical actions, such as those of baptism, matrimony and the Lord's Supper remain, these cannot simply be arbitrary and/or symbolic commands of the sort that were given in the Old Testament. The need for obedience here must be somehow grounded in reality. And the metaphysicalizer has an explanation here. Baptism changes the soul of the genuine participant, incorporating her into the Body of Christ in a mysterious way that goes beyond the symbolic and even beyond the performative (it is not just a human work—if it were a performative, it would be just a human work, and that is contrary to the focus on grace). Matrimony genuinely joins two people, not merely symbolically linking them together, not just being a performative, not even simply changing God's attitude to them ("making them married in the eyes of God"), but actually changing the people in a supernatural way that is quite mysterious, and that provides them with the grace to live out the pragmatic aspects. The Lord's Supper is commanded because in it, it is the Lord who offers himself quite literally to us for us to consume his flesh, thereby receiving the grace to live more fully as members of Christ's body.
Without metaphysicalizing, the distinction between the Old Testament and the New is obscured. The metaphysics provides a grounding for the normative effects. But without practicalizing, we have gnosticism.