"We Believe in One Baptism for the Forgiveness of Sins"
Answer: That their sins may be forgiven them in baptism."
St. Jerome, Against the Pelagians, 3:18(A.D. 415)
Point A) The early Church believed in the necessity of baptism for salvation based on Jesus words and the teachings of the apostles. Numerous writings from the early Church prove that infant baptism was the normative pathway for salvation.
Point B) The fathers of the reformation both believed and insisted on infant baptism as necessary for salvation. As a matter of fact, Luther and Calvin dealt severely with anabaptists (did not believe in infant baptism) calling them heretics, blasphemers and even worse.
Point C) Some modern day Christians believe that if you ask Jesus into your heart to be your Personal Lord and Savior, you are saved. Baptism is then later "required but not necessary" or for some, never required at all.
So how did we get from point A to point C in just 500 years? What is the truth? Is the Creed written by the early Church stating we believe in one baptism for the forgiveness of sins, wrong? Is this concept of baptism for the forgiveness of sins something we can dismiss easily because it doesn't fit our modern day view of baptism? Even if our view is diametrically opposed to both early christian writings or the theology of the reformers?
Here's what the early church and the reformers said about baptism:
St Augustine 400 AD:
Augustine,On Baptism against the Donatist,4:24:31(A.D. 400),in NPNF1,IV:461
"But as baptism is a solemn recognition by which God introduces his children into the possession of life [e.g., regeneration], a true and effectual sealing of the promise, a pledge of sacred union with Christ, it is justly said to be the entrance and reception into the Church. And as the instruments of the Holy Spirit are not dead, God truly performs and effects by baptism what he figures.”
“There is a union complementary with the thing figured, lest the sign be empty, because that which the Lord represents in sign he effects at the same time, and executes in us by the power of the Spirit . . . What indeed do we abrogate or take away from God when we teach that he acts through his instruments, indeed, he alone . . . God works . . . through the sacraments as instruments… The Spirit is the author, the sacrament is truly the instrument used.
"So then we must ever come to this point, that the Sacraments are effectual and that they are not trifling signs that vanish away in the air, but that the truth is always matched with them, because God who is faithful shows that he has not ordained anything in vain. And that is the reason why in Baptism we truly receive the forgiveness of sins, we are washed and cleansed with the blood of our Lord Jesus Christ, we are renewed by the operation of his Holy Spirit.
And how so? Does a little water have such power when it is cast upon the head of a child? No. But because it is the will of our Lord Jesus Christ that the water should be a visible sign of his blood and of the Holy Spirit. Therefore baptism has that power and whatsoever is there set forth to the eye is forthwith accomplished in very deed."
"That the Baptism of infants is pleasing to Christ is sufficiently proved from His own work, namely, that God sanctifies many of them who have been thus baptized, and has given them the Holy Ghost."
The One Holy Catholic and Apostolic Church:
"The Church affirms that for believers the sacraments of the New Covenant are necessary for salvation. "Sacramental grace" is the grace of the Holy Spirit, given by Christ and proper to each sacrament. The Spirit heals and transforms those who receive him by conforming them to the Son of God. The fruit of the sacramental life is that the Spirit of adoption makes the faithful partakers in the divine nature by uniting them in a living union with the only Son, the Savior."
For more on why Catholic baptize babies go here.