Fred Sanders in the Credo Magazine on how we arrive at the doctrine of the Trinity.
"The idea that we could read doctrines directly off our spiritual experience was a hallmark of classical theological liberalism, and did not normally promote the health of the doctrine of the Trinity (see the treatments of the doctrine by Schleiermacher and Ritschl, for instance). The doctrine of the Trinity doesn’t spontaneously emerge from spiritual experience;; it has to be carefully taught." (22)
Then later about how this learning reveals how Trinitarian the Gospel and our salvation is.
"When we know all of this, we know where the gospel came from. We know that in this work of human salvation, the character of God is made known to us, and that character is the triune character of Father, Son, and Holy Spirit. Taking the big view of how we know the details of the doctrine of the Trinity helps explain the odd situation we started with: that everyone who gets saved has had this deeply trinitarian experience, but few notice the trinitarian character of it." (24)
And finally an excellent comment about the place of the Trinity in the church.
"The doctrine of the Trinity is the quintessential catechizing doctrine. Whenever and wherever Christian churches have understood the urgency of the task of teaching the truth to believers, the doctrine of the Trinity has thrived: think of the fourth century and the sixteenth century, both periods rich in catechetical literature and practice. On the other hand, when the practice of catechesis has fallen into neglect, the doctrine of the Trinity has lost its luster "(25)
[Again my apologies for the weird formatting, cut and paste from a PDF]