As the word baptism is taken for the mere administration or external ordinance, so the internal covenanting or faith and repentance of the (adult) person to be baptized, is no essential part of it, nor requisite to the being of it; but only the profession of such a faith and repentance, and the external entering of the covenant; but as baptism is taken for the ordinance as performed in all its essential parts, according to the true intent of Christ in his institution (that is, in the first and proper meaning of the word); so the internal covenanting of a penitent, sincere believer, is necessary to the being of it. And indeed the word baptism is taken but equivocally or analogically at most, when it is taken for the mere external administration and action: for God doth not institute worship ordinances for bodily motion only; when he speaketh to man, and requireth worship of man, he speaketh to him as to a man, and requireth human actions from him, even the work of the soul, and not the words of a parrot, or the motion of a puppet. Therefore the word baptism in the first and proper signification, doth take in the inward actions of the heart, as well as the outward professions and actions. And in this proper sense baptism is the mutual covenant between God the Father, Son, and Holy Ghost, and a penitent believing sinner, solemnized by the washing of water, in which as a sacrament of his own appointment God doth engage himself to be the God and reconciled Father, the Saviour and the Sanctifier, of the believer, and taketh him for his reconciled child in Christ, and delivereth to him, by solemn investiture, the pardon of all his sins, and title to the mercies of this life and of that which is to come. What I say in this description of a penitent believer, is also to be understood of the children of such that are dedicated by them in baptism to God, who thereupon have their portion in the same covenant of grace.
The word baptism is taken in the first sense when Simon Magus is said to be baptized, Acts xxviii. And when we speak of it only in the ecclesiastic sense, as it is true baptism _in foro ecclesiæ_; but it is taken in the latter sense when it is spoken of as the complete ordinance of God, in the sense of the institution, and as respecting the proper ends of baptism, as pardon of sin and life eternal; and _in foro cœli_.
In this full and proper sense it is taken by Christ when he saith, Mark xvi. 16, "He that believeth and is baptized shall be saved;" that is, he that believeth, and is by baptism entered into the covenant of God; and in this sense the ancients took it, when they affirmed that all that were baptized were regenerated, pardoned, and made the children of God. And in this sense it is most true, that he that is baptized (that is, is a sincere covenanter) shall be saved if he die in that condition that he is then in.[40] All that the minister warrantably baptizeth, are sacramentally regenerate, and are _in foro ecclesiæ_ members of Christ, and children of God, and heirs of heaven: but it is only those that are sincerely delivered up in covenant to God in Christ, that are spiritually and really regenerate, and are such as shall be owned for members of Christ and children of God _in foro cœli_. Therefore it is not unfit that the minister call the baptized, regenerate and pardoned members of Christ, and children of God, and heirs of heaven, supposing that _in foro ecclesiæ_ they were the due subjects of baptism. But if the persons be such as ought not to be baptized, the sin then is not in calling baptized persons regenerate, but in baptizing those that ought not to have been baptized, and to whom the seal of the covenant was not due.
None ought to be baptized but those that either personally deliver up themselves in covenant to God the Father, Son, and Holy Ghost, professing a true repentance, and faith, and consent to the covenant; or else are thus delivered up, and dedicated, and entered into covenant in their infancy, by those that, being christians themselves, have so much interest in them and power of them, that their act may be esteemed as the infants' act, and legally imputed to them as if themselves had done it. If any others are unduly baptized, they have hereby no title to the pardon of sin or life eternal, nor are they taken by God to be in covenant, as having no way consented to it.