Please show where the NT writers said Mary was sinless.
. Please show where Jesus said we had to go to a priest for confession.
Please show where the NT said to build idols of Mary and pray to her.
. We can start with those for now.
Please show where the NT writers said Mary was sinless.
You're starting from false premises.
The first false premise is that the NT writers were mindful that the Church would have to convince several generations of skeptics who would not arrive on the scene until a millenium and a half later.
The second false premise is that the writers of the NT took pains to include absolutely every last detail about Christian dogma, liturgy, prayer and worship in the NT.
The third false premise is that the only source of Christian teaching is a book.
Jesus did not commission a book. He commissioned men....real, live human beings! Some of those men whom he commissioned subsequently recorded some of the events in Jesus' life, together with some of his teachings. Likewise, these men commissioned other men who evangelized in various parts of what is now the Middle East, Europe and Asia. Some of their writings to the fledgling Christian communities were likewise preserved in a book.
However, it should be noted that these men had lives apart from any book. Their evangelization did not depend on the New Testament because it didn't exist. For instance, when Paul and Barnabas got into a dispute in Antioch over circumcision, they could not say......"OK....what does it say in the New Testament" (as you just did). Instead, they returned to Jerusalem to consult with "the apostles and priests" as we're told. That's how the Church functioned and how disputes were resolved. No book.....no Bible reading.....just the elders of the Church.
This is the model of the Church which has come down to us to this day. The Bible does not give us the Church. That's bass ackwards.
Likewise, the Christians at Corinth and Ephesus did not receive Paul's letters as readings from the Bible. They received them as letters from the man who had evangelized them.
So in response to your question about where the Bible mentions the Rosary; it doesn't (although the events in the Rosary are described in the Bible).
But so what? It's an issue only for those who embrace the false premises I've listed above.
Jesus said to them again, “Peace be with you. As the Father has sent me, so I send you.” And when he had said this, he breathed on them and said to them, “Receive the holy Spirit. Whose sins you forgive are forgiven them, and whose sins you retain are retained.” (John 20:21-23)Now you please show me where in the NT it says the Bible alone.
Please show me where in the NT it says "this is my Body" does not mean exactly that.
Please show me where in the NT it says we are saved by faith alone.