More circular reasoning. Only the Roman church can interpret Gods word through the means of their tradition and teaching. If you disagree with the Roman church you disagree with God because only they can interpret Gods word.....rinse lather repeat
Thus while RCs attempt to appeal to Scripture for support of distinctive Catholic beliefs it does not teach, the weight of Scriptural substantiation is not their basis for assurance of Catholic teaching, as instead it is ultimately based upon the novel and unScriptural premise of ensured perpetual magisterial infallibility as per Rome. Which is why a typical recourse of Catholics when failing to establish distinctive Catholic beliefs via Scripture is to argue "we gave you the Bible" thus you need to submit to Rome. Which logic in principle invalidates the NT church.
But how do they know their church is the one true one? Because Rome has presumed to infallibly declare she is and will be perpetually infallible whenever she speaks in accordance with her infallibly defined (scope and subject-based) formula, which renders her declaration that she is infallible, to be infallible, as well as all else she accordingly declares. And around and around it goes.