Must a text regarding matters of creed be definitive in authenticity and definitive in meaning, or is it sufficient for it to be definitive in authenticity even if it is presumptive in meaning?

A Muslim worships according to what the texts of the Qur’an and Sunnah indicate, without differentiating between those of probabilistic or definitive indication. The assertion that certainty is a prerequisite for the evidences of beliefs is rejected because the blameworthy ẓann (conjecture/assumption) in the verses refers to doubt and mere guesswork, not the preponderant ẓann (strong probability) conveyed by the legal evidences. The Companions and the Successors acted upon probabilistic reports in matters of belief and other issues, and this is the stance of the majority of Ahl al-Sunnah.