Berean:
The mere fact that Luther and Calvin reformed was evidence of their ability to think for themselves. What you have said is contrary to history.
Let me provide a little more history to support what I claimed. You tell me if these quotes fit your understanding of baptism:
St. Augutine: “The Lord has determined that the kingdom of Heaven should be conferred only on baptized persons. If eternal life can accrue only to those who have been baptized, it follows, of course, that they who die unbaptized incur everlasting death” (St. Augustine, circa 400AD)
St. Augustine: “The fault of our nature remains so deeply impressed in our offspring as to make them guilty even when the guilt of the self-same fault has been washed away in the parent by the remission of sin. The guilt, therefore, of that corruption will remain in the carnal offspring of the regenerated (i.e… the baptized) until it also is washed away in them by the laver of regeneration Titus 3:5]. A regenerated man does not regenerate, but generates some according to the flesh. So his first birth holds a man in that bondage from which nothing but his second birth delivers him” (St. Augustine, “On Baptism of Infants”, circa 400 AD).
St. Aphraates: “From baptism we receive the Spirit of Christ. At that same moment in which the priests invoke the Spirit, heaven opens, and he descends and rests upon the waters, and those who are baptized are clothed in him. The Spirit is absent from all those who are born of the flesh, until they come to the water of rebirth, and then they receive the Holy Spirit. . . in the second birth, that through baptism, they receive the Holy Spirit.” (Aphraahat the Persian Sage, Treatises 6:14:4 [inter A.D. 340])
St. Clement of Alexandria: “When we are baptized, we are enlightened. Being enlightened, we are adopted as sons. Adopted as sons, we are made perfect. Made perfect, we become immortal . . . ‘and sons of the Most High’ [Ps. 81:6]. This work is variously called grace, illumination, perfection, and washing. It is a washing by which we are cleansed of sins, a gift of grace by which the punishments due our sins are remitted, an illumination by which we behold that holy light of salvation.” (Clement of Alexandria, The Instructor of Children 1:6:26:1 [A.D. 191])
The Bible: “And I will pour upon you clean water, and you shall be cleansed from all your filthiness, and I will cleans you from all your idols. And I will give you a new heart and put a new spirit within you: and I will take away the stony heart out of your flesh, and will give you a heart of flesh. And I will put My spirit within you: and I will cause you to walk in my commandments, and to keep my judgments, and to do them.” (Ezekiel 36:25-27)
Tertullian: “Without Baptism, salvation is attainable by no one” (Tertullian - On Baptism circa 200AD).
St. Ambrose: "Without Baptism, faith will not secure salvation, since only through Baptism comes the remission of sin and the special grace… When the Lord Jesus Christ was about to give us the form of Baptism, He came to John, and John said to Him: “I ought to be baptized by Thee, and comest Thou to me?” And Jesus, answering, said to him: “Suffer it to be so for now. For thus it becometh us to fulfill al justice” [Mt 3:14/15]. (St. Ambrose - “One the Sacraments” Bk 1 CSL 73)
"No one ascends to the kingdom of Heaven except by the Sacrament of Baptism. No one is excused from Baptism: not infants nor anyone hindered by any necessity. (St. Ambrose of Milam, “On Abraham” Bk 4, Ch 11:79)
Martin Luther. Even Luther realized that “Baptism is no human plaything but is instituted by God himself. Moreover, it is solemnly and strictly commanded that we must be baptized or we shall not be saved. We are not to regard it as an indifferent matter, then, like putting on a new red coat. It is of the greatest importance that we regard Baptism as excellent, glorious, and exalted” (Martin Luther, Large Catechism 4:6).
“No one can attain salvation without baptism, especially in view of the declaration of the Lord, who says, `Unless a man shall be born of water, he shall not have life’.” (Tertullian, Baptism 12:1 [A.D. 203])
That is the history of what the early Christians believed and taught. What you have been taught regarding baptism is no where to be found before the 16th century.