Basically the Catholic church. Although I must say I think the terms protestant and catholic need to be done away with. We just need to remember we are all Christians. The rest is just details.
I don't know what the name Protestant originally stood for. The disagreement is mainly about how a person is justified before God. Protestants tend to view saving faith, as glorifying God, leaning on the work of Jesus on the cross as enabling a trade, a swap, "He became sin who knew no sin that we might become the righteousness of God in HIm" Corinthians." Jesus righteous work on the cross counted for our account and our sin paid for.
The disagreement is mostly regarding the nature of the true gospel and how a person is saved and also how a person stands in good conscience before God.
The historical Protestant view is like this
Saving Faith ---> leads to ---> Good works and Salvations
(both good works and salvation are a fruit of salvation, a person being saved by grace and the saving is evidenced by works but not caused by works)
The historical Catholic view is like this
Saving Faith together with Good works --> lead to ---> Salvation
(good works are a necessary prerequisite of salvation)
Actually the word "Protestant" doesn't mean "protest" in the modern sense of the word. It was a positive protest", synonym to "proclaim". Before the rulers, the representatives of the Reformers said: "We protest that..." and then listed their beliefs.
Historically, because of the corruption of the Catholic church in getting rich because of "Penance," and the practice of "praying a soul out of purgatory" where they pocketed much of the fees, and charged more to those that had more, Martin Luther began to see the futility of "confession" to an earthly priest. Coupling that with the New Testament example of Christ as our only High Priest, he challenged the Catholic position of denying mankind the "common" priesthood, which states that we aren't good enough to pray directly to God, but have to pray to the priest, who in turn takes our prayers to God for us.
(Hebrews 4:14 ?Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession.
15 ?For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.
16 ?Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.)
Based largely on these scriptures, and those in the following chapter and other scriptures, Luther surmised that each man woman Boy or girl could bow and pray directly to God, through Jesus, who had now taken his place in heaven as our high priest, and that going to the earthly priests was to deny the accomplishments of Jesus Christ at Calvary. That, in a big nutshell is the gist of protestantism.
What has Protestantism historically tended to protest against?
