Bearing this in mind, let us now turn to the doctrine of the Trinity. This is expressed in vv. 3-6 of the Athanasian Creed as follows:—
3. 'The Catholic Faith is this, that we worship one God in Trinity, and Trinity in Unity.
4. 'Neither confounding the Persons, nor dividing the Substance.
5. 'For there is one Person of the Father, another of the Son, and another of the Holy Ghost.
6. 'But the Godhead of the Father, of the Son, and of the Holy Ghost, is all one, the Glory equal, the Majesty co-eternal.'
Here, it will be noticed, vv. 5 and 6 give the reasons for v. 4, so that the Godhead in v. 6 is, as we should have expected, the same as the Divine Substance or Nature in v. 4. Thus the meaning is as follows:—
We must worship one God (as to Nature) in Trinity (of Persons) and Trinity (of Persons) in Unity (of Nature); neither confusing the Persons, for each is distinct; nor dividing the Nature, for it is all one.
Thus far there is no intellectual difficulty in the statements of the Creed. We do not mean that there is no difficulty in believing them to be true, or in accurately defining the terms used; but that, as statements, their meaning is quite intelligible.
We now pass on to the following verses which are deductions from this, and show that as each of the three Persons possesses the Divine Nature, all attributes of the Godhead (i.e., of this one Divine Nature) are possessed by each of the three. Each is therefore eternal, and yet there is only one eternal Nature. But this is expressed in a peculiarly short and abrupt manner. No one, of course, supposes that God is Three in the same sense in which He is One, but the Creed does not sufficiently guard against this, perhaps because it never occurred to its author that anyone would think it meant such an obvious absurdity. Moreover, even grammatically the verses are not very clear. For the various terms uncreate, incomprehensible (i.e., boundless, or omnipresent), eternal, almighty, God, and Lord are used as if they were adjectives in the first part of each sentence, and nouns in the latter part.
But we must remember these verses do not stand alone. If they did, they might perhaps be thought unintelligible. But they do not. As just said, they are deductions from the previous statement of the doctrine of the Trinity; and, therefore, they must in all fairness be interpreted so as to agree with that doctrine, not to contradict it. And the previous verses (3-6) show clearly that where three are spoken of, it refers to Persons; and where one is spoken of, it refers to Substance or Nature.