God knew that the New Testament was going to be used for at least 2000 years. He knew that Christianity was going to split off into 30000 odd denominations during this 2000 years with each denomination claiming their interpretation of the Bible as correct.
Many denomination teach different doctrines. Jesus did knew that Christianity will split but he prayed to the Father that they (us) will be One. He does not like it when the East-West Schism happened, nor did he like the Reformation. Jesus is about unity not division.
In Protestantism (the doctrine not the people), there is great division. There are over 1,000 of Protestant Denominations, like the Baptists, Methodist, Lutheran, Evangelical Christians, Anglican, Episcopalians, Assembly of God, Calvinists, Non-Denomination, etc.
The Catholic Church on the other hand, teaches one faith, one baptism, same doctrines. The Magisterium, the bishop in union with the Pope have these teaching authority. There is no different doctrine.
Yes, there are so called Catholics who teach something contrary to the teachings of the Church but they are in error. The final authority is the Magisterium. It teaches infallible teachings on all moral and faith issue.
The authority of the Church comes from God. Since Jesus granted the Apostle authority, and the apostles handed their authority down to their sucessors.
Surely if the Bible is God’s word then he could have (should have) done something about it, not?
The Bible is God’s word but God established Christianity upon the Church first. The Bible came second.
Yes, there was the Scripture before the Church. It was just the Old Testament. There was no final canon of Scripture until late 300 A.D in the Council of Rome, Council of Hippo, and Council of Carthage. These Church Council compilled a list of Books both Old Testament 73 OT text, and 27 NT text.
Later on by the Reformation, the Protestant leaders remove 7 books in the OT. Martin Luther in his translation remove the Letter of James, and have doubt with the Book of Revelation. He didn’t add those books until he was pressured by other Protestants to keep them.
As a previous poster explained, there is no circularity if you accept the Bible as God’s inerrant word. So for the purposes of this argument I concede.