Nor the trinity, the New Testament, salvation by faith alone ( that on took about 1500 years to get invented) etc...
Really?
- The trinity is strongly hinted at in the Old Testament and explicitly taught in the New Testament. For example, Matthew 3:16-17 says "After Jesus was baptized, he came up from the water and behold, the heavens were opened (for him), and he saw the Spirit of God descending like a dove (and) coming upon him. And a voice came from the heavens, saying, "This is my beloved Son, with whom I am well pleased."
As another example, Matthew 28:19 says, "Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit..."
Finally, John 1 says that, from the beginning, "the Word was with God and the Word was God."
The New Testament is rather plain, I think, in presenting the fact that God the Father, God the Son, and God the Holy Spirit are three persons in one being. There was a great debate at Nicaea, of course, almost three hundred years after the church was founded but the dissenters were silenced -- not by any new revealed doctrine -- but by the church affirming what scripture plainly taught.
- The New Testament in most cases was received by the church as the individual books were written (Hebrews was one example to the contrary). For example, 1 Peter 3:15-16 says "And consider the patience of our Lord as salvation, as our beloved brother Paul, according to the wisdom given to him, also wrote to you, speaking of these things as he does in all his letters. In them there are some things hard to understand that the ignorant and unstable distort to their own destruction, just as they do the other scriptures." It didn't take a church council to decide that Paul's writings were scripture -- they were accepted as scripture because Paul was an apostle and demonstrated the attributes of an apostle.
- Luther didn't "invent" the doctrine of salvation by faith alone -- it is the teaching of scripture and was the belief of the early church. Catholics and Protestants both often misunderstand the doctrine. It is more properly stated like this: We are saved by grace alone through faith alone in Christ alone and the kind of faith that saves is the kind of faith that produces good works. Read that again and then do a scripture study on salvation -- it will become crystal clear to you. I provide cites to several verses (and I don't just do this for my entertainment, you know!) but there are plenty of other passages which support this doctrine.
When Jesus was asked (John 6:29), "What can we do to accomplish the works of God?" Jesus replied "This is the work of God, that you believe in the one he sent." Faith plus works is not required for salvation -- see the entire book of Galatians for a refutation of this false notion.
John wrote that "Whoever believes in the Son has eternal life." (John 3:26). Paul, and especially James, expanded upon the words of Jesus and said that even though only faith is required, we demonstrate that we have saving faith by the works that we do.
God saved us in order to do good works, not because we've already done good works. "For we are his handiwork, created in Christ Jesus for the good works that God has prepared in advance, that we should live in them" (Ephesians 2:10).
If we claim we are saved but do not bear the fruit of good works, then we aren't really saved: "They claim to know God, but by their deeds they deny him" (Titus 1:16).
So, in summary, none of the doctrines you mentioned were discovered or "invented" later -- they are part and parcel of the teachings of the New Testament and were believed and taught by the early church.