How does the audience to which Romans was written, in any way, support the idea of a 3 step new birth?
We all know UPC pastors will not stop teaching the
Acts 2:38 message to their congregations.... why? Because they want to safeguard their message. They want to make sure their version of truth is carried on without compromise. I submit that the notion the epistles do not contain salvational truth just because they are directed to "saved people" is an extremely weak, if not fully invalid, proposition. Many things are written in the epistles in answer to legalism, gnosticism, and other false issues which began to creep into the congregations.
The epistles hold full salvational truth because they are written to safeguard the truth against heresy. That the 3 step view is not presented is strong evidence the view was not thought of as truth to be safeguarded.