If there is an essential role for the core, specifically Christian canonical scriptures, I think it is to ground a conception of the good.
It is one thing to say God is the Good, or a Christian ought to align their will with the good. It is another to say exactly what the good is.
Here, the Gospels and letters from Paul, John, and James, in particular, have to be a significant part of a specifically Christian answer.
This doesn’t require something like ‘infallibility’ or ‘inerrancy’ in that scripture. Rather, scripture can be a repertoire that can act as an heuristic, and so on.