Trinitarian Monotheism can be explained but not fully comprehended
In church history, Saint Augustine (354-430) probably thought more about the doctrine of the Trinity than any other uninspired writer—with the possible exception of John Calvin. There is an unconfirmed story about Augustine walking upon the ocean’s shore, greatly perplexed about the doctrine of the Trinity. As he meditated, he observed a little boy with a sea shell, running to the water, filling his shell, and then pouring it into a hole which he had made in the sand.
“What are you doing, my little man?” asked Augustine.
“Oh,” replied the boy, “I am trying to put the ocean in this hole.”
Learning his lesson Augustine exclaimed, “That is what I am trying to do. Standing on the shores of time I am trying to get into this little finite mind things which are infinite.”
An Argument for Christian Monotheism Against Islamic Monotheism