This is Peter’s answer to the question propounded by Christ to the Apostles. The question was about their judgment and faith, as to the person of our Saviour. The answer contains the confession of the Disciples concerning Christ, and together with this, a description of Christ. In this description, the person of our Saviour is described, 1. From his office, You are Christ. 2. From his essence, which is indicated by his essential relation to that principle from which he came forth. This principle is God, who is illustrated by his attribute of life, the living God. The relation of our Saviour to God is that of a Son to a Father, the Son of the living God. And he is also illustrated by a tacit comparison of that unlikeness that exists between the Son and others that use the same name. And this comparison is illustrated to us in the particle prefixed to Son: the Son, or that Son.
Doctrine 1. Jesus Christ is the coeternal or natural Son of God.
He is called the Son of God because he proceeds from the Father, not by way of creation, but by way of generation. And generation is used here by similitude or proportion: this emanation of the Son from the Father has with that production what a child has from its parent. In comparing this similitude or analogy, as it is in all the other attributes of God, the perfections only of the denomination are understood to agree; and all the imperfections and defects are to be removed in our thoughts. Hence, what is proper to bodily generation — that the one who begets does it with some transmutation; and the thing begotten is something out of the begetter — these are not to be imagined in this divine mystery. Nor is it to be imagined in spiritual generation in or by a creature — that the thing begotten is of another essence from that of the begetter — as in the production of the word of the mind in human understanding. But the perfection that is in the generation of a body — that the begotten is in essence and nature like the begetter — is here conjoined with that perfection that is found in spiritual generation of creatures — that the begotten is in the begetter by the most inward and inseparable way of being so. And so we come nearest to apprehending what can be conceived or apprehended of this divine generation of the Son by the Father. For in Christ proceeding from God the Father, he has the same common nature and essence with the Father, and is his substantial image, Heb 1.3. Yet he still remains in the Father, and the Father in him, without total separation of either from the other; just as God understanding himself, is in God understood by himself; and God understood by himself, is in God understanding himself.
Use 1. Of Consolation: towards all believers because while they have communion with Christ, who is the Son and heir of all the goods of the Father, they may from this see their felicity, namely that they are coheirs with Christ in the heirship of life and eternal glory, Rom 8.17.
Use 2. Of Admonition: to all, so that they hear the voice of Christ with all submission according to that command sent down from heaven, This is my Son in whom I am well-pleased; hear him, Mat 17.5.
Doctrine 2. Christ is the Son of God in a far more perfect and divine way than any creature is.
This is from the particle the, or that Son. The reason is because Christ is the Son of God by nature, not by adoption or creation. Christ is called the natural Son of God, not because in his first or proper nature he is the Son of God; for so the good Angels may be called the natural Sons of God if they are compared with men who now, after the fall, are not thus the natural sons of God, but only in their second nature and generation — that is, in their regeneration and adoption. But Christ is the natural Son of God, because the Father begot him, not of free choice, or decree of wisdom and will going before it, but of natural necessity, just as light engenders light. Moreover, Christ has the same most single and singular nature with the Father, of which there can be no resemblance found on earth in any creature except that which is imperfect. Therefore Christ is also called the only Son of God and the only begotten. For though, as to the general denomination, he has many whom he grants to call brothers, yet as to the special manner and foundation of this filiation of his, he has no brothers at all, nor any like himself, nor can he have any.
Use 1. Of Direction: of our Faith and thoughts about Christ. For though in our relation to God, we use the same words to speak of Christ and of ourselves (because we lack more specific and proper expressions) — thus God is called the father of Christ, and our Father, and we together with Christ are called the sons of God — we should always conceive that all divine perfection are in these titles and words when they are attributed to Christ; and these same words, when they are attributed to us, should have a far inferior dignity; and yet a dignity that is sufficient enough for our consolation.
Use 2. Of Information: how we ought to seek all that belongs to our adoption and happiness only in Christ, and by Christ — because Christ is that son of God in whom is the principality and all the excellence of the divine filiation, or sonship. Therefore it is in him, and by him, that we should always seek all our participation in this dignity that we can have, or may crave.
Doctrine 3. Christ is the Supreme Lord in the Church of God.
Though this is not expressed in our Text, yet because it is in order conjoined with the antecedent words in the Apostles Creed (commonly called), it will be conveniently joined to the preceding matter in this passage. It is thus gathered from our Text. Peter in the words set down, refers to the Messiah, whom all the Prophets had preached, saying that he would be a King, a Lord, and a most glorious vindicator or restorer of his people. And it is also to this that the particle the or that looks in part. For the Jews at that time looked for such a Messiah, as appears from Joh 1.49, You are that Son of God, you are the King of Israel, as it is also stated in the words of the High Priest, Mat 26.63. And Christ, in his answer explains the matter, how his dominion is contained in these words.
Reason 1. Because Christ is one and the self-same God with the Father; and God is the Lord of all that he made, in the order of grace, as well as of nature; so also Christ is the Lord of them all by right of creation; for by him all things were made, and by right of sustenance, because he sustains all that he made, with his mighty hand, Heb. 1.3.
Reason 2. Christ is Mediator, and is Lord of the Church by right of Redemption. For he that redeemed the whole, bought the whole man for himself; therefore he has him in his power, in whole and in part, and he has that by a debt of justice, to which also accrues another debt of thankfulness. This is why it comes to pass that the one who is redeemed wholly yields and surrenders himself to his Redeemer.
Reason 3. Just as Christ is considered the party to whom we subject ourselves, and who obliges our truth and fidelity to him by a most holy Sacrament, oath, or vow which is solemnly sealed with an outward badge or confession — so he is our Lord by right of contract or bargain of Covenant, of our religious assurance or truth-giving, and of our promise. And for these two last reasons, more specifically and especially, everywhere in the New Testament he is called our Lord — even when he is named together with the Father and with the Holy Spirit; because he alone is thus our Lord in our nature; he alone is our Lord, who thus alone redeemed us. Lastly, we in a special way choose him to be our Lord, in our calling to Faith by our answer of a good conscience, as Peter calls it. It is from this also that we are called Christians, or subjects of Christ and of his Kingdom, and that we call upon his name, just as his name is called upon us, and it is professed that he is our Lord.
Use 1. Of Instruction: to establish our Faith concerning the Godhead of Christ, because none either can or may be called our Lord absolutely, or God of the Church, except God alone. For,
First, only God is the Lord of man’s life, and of those things which belong to the goods of nature. For Magistrates and Commonwealths are, only by God’s institution, keepers of the lives of their subjects under them, in order for the public good of all. And every Citizen or Subject is but a tutor and keeper of his own life, and not an absolute Lord or maker of it.
Secondly, only God may use, or apply to his use, the whole man according to his own free arbitrement.
Thirdly, the things that belong to the goods of grace are of a nobler rank than those of nature. Therefore, if God alone is Lord of this natural life, than much more must it be granted that he alone is Lord of grace and spiritual life.
Fourthly, the one that discharges the part of the Lord of the Church of God, should by necessity be omniscient, omnipotent, and omnipresent, because it belongs to him to have the care over the Church, and all its members dispersed all over the earth, and under the whole compass of heaven, and to direct them in all their ways, and defend them against all sorts of evils, and lastly, to heap upon them all sorts of good to their happiness.
Seeing then that this is the solemn title of Christ, that he is Lord in the Church of God, it necessarily follows that he is also essentially and by nature God, and not by office only.
Use 2. Of Consolation: to all the faithful, that they have him for their Lord, who gave himself unto death for them.
Use 3. Of Admonition: that we subject ourselves wholly to this Lord, and to his will, and do him all honour in all and every part of our life and conversation.
From The Substance of Christian Religion by William Ames