Augustine
- Augustine believed that the purpose of marriage is procreation, and that lust during sex—even among married Christians—was wrong.
- Augustine believed that the use of contraception to prevent children was perverting the purpose of marriage, "committing adultery within marriage" and "turning the bed-chamber into a brothel."
- Augustine believed that if you are going to teach Scripture, you must have a knowledge of the natural world, mathematics, music, science, history, the liberal arts, and a mastery of dialectics (the science of disputation).
- Augustine believed that sacramental baptism produces regeneration and is necessary for the forgiveness of sins.
- Augustine believed it was permissible to use force against heretics.
- Augustine believed that the Lord's Supper (the Eucharist) was necessary for salvation.
- Augustine held to a dualistic view of the world, which was heavily influenced by non-Christian philosophy.
- Augustine believed that a person can fall from grace and lose their salvation.
- Augustine believed that Mary (mother of Jesus) was a perpetual virgin.
- Augustine believed in praying for the dead.
- Augustine believed infants were subject to eternal death unless baptized (baptismal regeneration).
Martin Luther
- Luther despised Jewish people, believing that they deserved persecution (theologically based, not racially based).
- Luther held to several shocking views about marriage and sex.
- Luther denied the canonicity of the books of Hebrews, James, Jude, and Revelation.
- Luther believed it was justified—and even divinely ordered—that civil disobedience be punished severely, as demonstrated in the Peasant's War.
- Luther believed that heretics should be put to death.
- Luther believed that writing in anger, using profanity, and shaming his enemies by name-calling was justified.
- Luther believed that all physical ailments were the work of Satan.
- Luther ridiculed and disparaged some of his opponents in the Reformation.
John Calvin
- Calvin believed that executing some unrepentant heretics was justifiable.
- Calvin believed that the Eucharist provides an undoubted assurance of eternal life.
- Calvin believed it was acceptable to lambaste his opponents with vicious names.
- Calvin believed that some of the Old Testament capital offences should be enforced today.
- Calvin believed that Jewish people were impious, inauthentic, and lacked common sense.
Charles Spurgeon
- Spurgeon believed smoking cigars was not wrong, and that it could be done "to the glory of God."
- Spurgeon believed going into debt was not acceptable. [He wasn't wrong.]
- Spurgeon thought the idle (those who didn't work) were beyond hope and it wasn't worth wasting time trying to improve them.
- Spurgeon did not believe in allowing music in worship.
- Spurgeon leaned Left in his politics.
- Spurgeon believed that the supernatural healing of sicknesses still occurred. [My understanding of this is that he prayed for the sick and they were remarkably healed. I don't think he believed in supernatural healing by means of laying on of hands.]
- Spurgeon believed that even the strongest of Christians may face seasons of depression, despair, and doubt. [He wasn't wrong.]
- Spurgeon believed he heard God's voice, and it told him to keep preaching without a college education (though he does not say whether the voice was audible or a mere impression).
- Spurgeon believed in what some would call giving "prophetic words" to people, knowing things about them beyond natural means.
- Spurgeon believed God answered the prayers of people before they were converted to Christ.
Martin Luther was correct in that the word "priest" finds its roots in both the pagan religions and the Jewish religion. He was also correct in detesting the word "church" as a translation for ekklesia, which refers to an assembly or a congregation of those called out from the world and to God.
John Calvin was correct in that all humans are born in sin and deserving of eternity in Hell, but that God saves certain ones by His grace and leaves the rest to themselves. You see this with the elect angels; you see this with choosing Israel over other nations; and you see this with regard to the many individuals within Israel over other individuals, including older family members.
Charles Spurgeon was correct in believing that ordination was not important [see God's Ordination Requires Not Approval of Men]. He was also correct in being against the use of honourific titles [see Do Not Be Called "Pastor" and Do Not Revere A Reverend!].