The Trinity is frequently, indeed, usually, discussed in rather abstract, theoretical terms. Expounding and debating various philosophical models of the Trinity.
Of late, the Trinity is coming under increasing attack on various fronts. There are different culprits. The Trinity is offensive to Muslims. The Trinity is an obstacle to ecumenists like the late John Hick. And the Trinity has been targeted by Unitarians like Dale Tuggy. Strikingly, we even see the reputation of “semi-Arians” like Samuel Clarke rehabilitated by some followers of Gordon Clark.
Overemphasis on the theoretical or philosophical aspects of the Trinity can obscure the indispensable practical value of the Trinity in Christian piety. Let’s pause for a moment how much the Trinity contributes to our understanding of God.
Consider how much we learn about God when we read about Jesus in the Gospels. How much we learn about God by observing Jesus in the Gospels. Eavesdropping on Jesus in the Gospels. Watching him. Hearing him.
Then consider how much less we’d know about God if Jesus wasn’t the Incarnate Son of God. Consider how much less we’d know about God if we didn’t have the Gospels. If we didn’t have that historical record of a time when God came to dwell among us.
Likewise, consider how much the Spirit teaches us about God. For the Spirit is the primary author of Scripture. The agent of inspiration.
Without the Spirit, we wouldn’t have the Bible. Consider how much less we’d know about God without the Bible.
Try to mentally blank out Jesus, then consider what’s left in your knowledge of God. Try to mentally blank out the Spirit's role in giving us the Scriptures, then consider what’s left in your knowledge of God. This is so engrained in Christian consciousness–and rightly so–that it’s almost unimaginable to consider the cost of losing it.
Moreover, absent the Trinity, not only would we know less about God, but there would be less about God to know. Indeed, we’d know less about a lesser God. For a unitarian deity is a very different kind of deity. A more distant deity. Unitarians deny the Incarnation.
And a unitarian deity has no internal social life. No inner fellowship. In that respect, he has far less in common with social creatures like human beings than a Trinitarian God.
A unitarian deity is more in the nature of a background condition, like the way time or logic conditions our existence. He’s the ground of being, but not much else. An existential precondition rather than an object of worship. Less a person than a principle. Not someone you look up to. Not someone whose character informs your ideal of goodness. You trust him (or it) in the sense of trusting the law of gravity.