I. The Definition, Nature, and Institution of Baptism
"Baptism is the initiatory sign by which we are admitted to the fellowship of the Church, that being ingrafted into Christ we may be accounted children of God." [John Calvin - Institutes]
"Baptism now is a washing." "Baptism is a sacred rite instituted by Christ in the New Testament, by which we are washed with water in the name of the Father, and of the Son, and of the Holy Ghost, to signify that God receives us into his favor, on account of the blood which his Son shed for us, and that we are regenerated by his Spirit; and that we, on the other hand, bind ourselves to exercise faith in God, and to perform new obedience to him."
"In the name of the Father, and of the Son, and of the Holy Ghost: The words in the name of, signify, 1. That baptism was instituted by the command and authority of the three persons of the Godhead in common, and that they command that those who will be members of the church should be thus baptized." "Baptizing them: that is, all those who come unto me through your teaching, and are made my disciples."
II. The Double Washing: Expiation and Regeneration
"There is in baptism a double washing: an external washing with water, and an internal washing with the blood and Spirit of Christ." "To be washed with the blood of Christ, is to receive the pardon of sin, or to be justified on account of his shed-blood."
"To be washed with the Spirit of Christ, is to be regenerated by the Holy Spirit, which consists in a change of evil inclinations into those which are good, which the Holy Ghost works in the will and heart, so as to produce in us hatred to sin, and a desire to live according to the will of God." [Zacharias Ursinus - Commentary on the Heidelberg]
"The first object, therefore, for which it is appointed by the Lord, is to be a sign and evidence of our purification, or (better to explain my meaning) it is a kind of sealed instrument by which he assures us that all our sins are so deleted, covered, and effaced, that they will never come into his sight, never be mentioned, never imputed." "Another benefit of baptism is, that it shows us our mortification in Christ and new life in him."
III. The Outward Element and Mode of Administration
"Whether the person baptised is to be wholly immersed, and that whether once or thrice, or whether he is only to be sprinkled with water, is not of the least consequence: churches should be at liberty to adopt either according to the diversity of climates, although it is evident that the term baptise means to immerse, and that this was the form used by the primitive Church." [John Calvin - Institutes]
"Yet the water is not changed into the blood or Spirit of Christ, nor is the blood of Christ present in the water, or in the same place with the water. Nor are the bodies of those who are baptized washed with this visibly; nor is the Holy Spirit, by his substance or virtue, more in this water than elsewhere; but he works in the hearts of those who are baptized in the lawful use of baptism, and sprinkles and washes them spiritually by the blood of Christ, whilst he uses this external symbol as a means, and as a visible word or promise to stir up and confirm the faith of those who are baptized."
"The sacraments are used lawfully, when the faithful, or such as are converted observe the rites which God has instituted, as signs of grace, and pledges of his will to them." "Such rites as have been added to baptism by men, as the consecration of the water, tapers, exorcisms, anointing with oil, salt, crosses, spittle, and things of a similar character, are justly condemned in the church of Christ, as corruptions of the sacraments."
IV. Infant Baptism and the Covenant Succession to Circumcision
"Are infants also to be baptized? Yes, for since they as well as the adult are included in the covenant and church of God; and since redemption from sin by the blood of Christ, and the Holy Ghost, the author of faith, is promised to them no less than to the adult; they must, therefore, by baptism, as a sign of the covenant, be also admitted into the Christian Church, and be distinguished from the children of infidels, as was done in the old covenant or testament by circumcision, instead of which baptism was instituted in the new covenant."
"Those unto whom the things signified belong, unto them the sign also belongs, unless there be some condition in the way of using it which would forbid it, or unless there be some circumstance connected with the institution which would not admit of the observance of the rite, as females formerly were debarred from circumcision on account of their sex, and as infants at this day are excluded from the Lord's Supper because of their incapacity of shewing the Lord's death, and proving themselves."
"Baptism occupies the place of circumcision in the New Testament." [Zacharias Ursinus - Commentary on the Heidelberg]
"The covenant is common, and the reason for confirming it is common. The mode of confirming it is so far different that they had circumcision, instead of which we now have baptism." "Hence it follows, that the children of believers are not baptised, in order that though formerly aliens from the Church, they may then, for the first time, become children of God, but rather are received into the Church by a formal sign, because, in virtue of the promise, they previously belonged to the body of Christ." [John Calvin - Institutes]
V. The Singularity and Perpetuity of Baptism
"From this it is evident why baptism is not repeated; because it is the sign of our reception into the favor and covenant of God, which remains for ever sure and valid in the case of those who repent." "We are born but once, and renewed but once: for he who is once truly ingrafted into Christ, is never wholly cast away: for 'him that cometh to me,' said Christ, 'I will in no wise cast out.'" [Zacharias Ursinus - Commentary on the Heidelberg]
"We ought to consider that at whatever time we are baptised, we are washed and purified once for the whole of life. Wherefore, as often as we fall, we must recall the remembrance of our baptism, and thus fortify our minds, so as to feel certain and secure of the remission of sins." "Although all men should be false and perfidious, yet God ceases not to be true, (Rom. 3: 3, 4;) though all were lost, Christ remains safe. We acknowledge, therefore, that at that time baptism profited us nothing, since in us the offered promise, without which baptism is nothing, lay neglected." [John Calvin - Institutes]