Sola Scriptura, “Scripture alone,” is the formal principle of the Protestant Reformation. Protestants claim to go by the Bible alone. So why do they disagree about so many things? Lutherans teach from the Bible that baptism regenerates and justifies. Baptists claim the Bible teaches the opposite. Presbyterians and other Reformed Protestants say the Bible teaches infant baptism. Baptists say it teaches baptism for believers only. Some Protestants say the Bible teaches that believers can lose their salvation. Others claim it teaches “once saved, always saved.” Some say the Bible teaches a pretribulation rapture. Others reject that entirely based on their own reading of the same Bible. Calvinists say Christ died only for the elect. Most other Protestants say He died for all. Beyond these, sincere Bible-reading Protestants have reached contradictory conclusions on the Lord’s Supper, church government, women in ministry, the millennium, Sabbath observance, and predestination. A Protestant might argue that these are merely secondary doctrinal disagreements. But where does the Bible itself classify doctrines as “primary” or “secondary”? Lutherans regard baptism as a primary doctrine. Calvinists regard limited atonement as a primary doctrine. And how can the question of whether baptism regenerates be called secondary when the Bible places such extraordinary emphasis on it? Jesus tells Nicodemus that no one can enter the kingdom of God without being born of water and the Spirit (John 3:5). He declares that “whoever believes and is baptized will be saved” (Mark 16:16). He commands His Apostles to baptize all nations as the means of making disciples (Matthew 28:19-20). Peter tells the crowd at Pentecost to “be baptized for the forgiveness of your sins” (Acts 2:38). Peter writes that “baptism now saves you” (1 Peter 3:21). If God intended the Bible to serve as the sole, sufficient rule of faith, why can’t Spirit-filled, Bible-reading Protestants agree on whether the sacrament Christ Himself commanded produces the regeneration He said was necessary for entering the kingdom of God? Why are there so many Protestant denominations that claim to go by the Bible alone yet teach so many contradictory interpretations of it?