[Luther] adds that human language is too limited to express adequately the lofty article of the Trinity; this doctrine so far surpasses human understanding that God as a kind Father will condone stammering and prattling of His children so long as their faith is correct; this term expresses the Church's faith as well as can be done in human language, for the word Trinity conveys the Christian knowledge of God, namely, that the Divine Majesty is three distinct Persons in one divine essence. (St. L. XII:628 f.)
-- F. Pieper, "Doctrine of God" from Christian Dogmatics, Vol. I