We all believe it; we must believe it if we would be saved. But no one of us can perfectly understand it. St. Patrick, you know, is said to have illustrated it to his converts by showing them the shamrock with its three leaves on one stem; but, of course, he never pretended that this was a perfect explanation of it. No perfect explanation of it can be given to us.
And why not? Is it because it really has no explanation? No, but because we are not able to understand the one which might be given. Explain the solar system to a child of five years: will he understand you? It is something the same with us and this greater mystery of God.
Some people, especially at the present day, who consider themselves very wise, say to themselves and to others: "Oh! this doctrine of the Trinity cannot be true." Ask them why not, and they will say: "Because we cannot understand it; it seems to us to be nonsense."
Well, what does their argument amount to? Just to this: "If the doctrine were true we should understand it; but we don't understand it, therefore it is not true."
"If it were true," they say, "we should understand it." And why? "Why, of course, because we are so wise that we can understand everything. It is well enough for stupid people, like those benighted Romanists, to believe what they don't understand, but such a proceeding would be quite below our dignity and intelligence. It is quite absurd to suppose that there is any mystery so deep that we cannot see to the bottom of it."
Now, I do not want to accuse these worthy people of any one of the seven capital sins; they are, no doubt, as good as they are wise. But there is something in what they say that looks just a little bit like one of those sins; like the first and most deadly of them all: that is, the sin of pride. And there is not much doubt that pride has in some form or other had something to do with all heresies; so I am afraid that those who deny the Holy Trinity are not quite free from it.
You think so, my brethren, I have no doubt. But, after all, are you not perhaps guilty of a little of the same sin yourselves? You believe in the Holy Trinity, it is true, but are there not some other things which you do not fully believe, though you ought to, and for very much the same reason?
God has given you the gift of faith; and you are willing to believe what you know to be of faith, even if it be beyond your reason, especially if it be something, like the Holy Trinity, beyond the reason of any one else. But are you not sometimes rather unwilling to believe other matters of religion, for which there is good authority, just because you, with your present lights, do not quite see through them? That is just the trouble with the heretics of whom I have spoken; is it not so with you, too, perhaps?